Surgical instrument with user adaptable techniques

ABSTRACT

A method for coagulating and dissecting tissue. The method includes measuring a tissue property and delivering multiple energy modalities to the tissue based on the tissue property. The energy modalities being delivered from a generator either alone or in combination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 15/177,430, entitled STEPPED STAPLE CARTRIDGE WITH ASYMMETRICAL STAPLES, filed Jun. 9, 2016, which application claims the benefit of U.S. Provisional Application Ser. No. 62/186,984 filed Jun. 30, 2015, U.S. Provisional Application Ser. No. 62/235,260, filed Sep. 30, 2015, U.S. Provisional Application Ser. No. 62/235,368, filed Sep. 30, 2015, U.S. Provisional Application Ser. No. 62/235,466, filed Sep. 30, 2015, U.S. Provisional Application Ser. No. 62/279,635, filed Jan. 15, 2016, and U.S. Provisional Application Ser. No. 62/330,669, filed May 2, 2016, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure generally relates to ultrasonic surgical systems and, more particularly, to ultrasonic and electrosurgical systems that allows surgeons to perform cutting and coagulation and adapt and customize techniques for performing such procedures based on the type of tissue being treated, employing multiple energy modalities based on tissue parameters, based on tissue impedance, and employing simultaneous energy modalities based on tissue parameters.

BACKGROUND

Ultrasonic surgical instruments are finding increasingly widespread applications in surgical procedures by virtue of the unique performance characteristics of such instruments. Depending upon specific instrument configurations and operational parameters, ultrasonic surgical instruments can provide substantially simultaneous cutting of tissue and hemostasis by coagulation, desirably minimizing patient trauma. The cutting action is typically realized by an-end effector, or blade tip, at the distal end of the instrument, which transmits ultrasonic energy to tissue brought into contact with the end effector. Ultrasonic instruments of this nature can be configured for open surgical use, laparoscopic, or endoscopic surgical procedures including robotic-assisted procedures.

Some surgical instruments utilize ultrasonic energy for both precise cutting and controlled coagulation. Ultrasonic energy cuts and coagulates by vibrating a blade in contact with tissue. Vibrating at high frequencies (e.g., 55,500 times per second), the ultrasonic blade denatures protein in the tissue to form a sticky coagulum. Pressure exerted on tissue with the blade surface collapses blood vessels and allows the coagulum to form a hemostatic seal. The precision of cutting and coagulation is controlled by the surgeon's technique and adjusting the power level, blade edge, tissue traction, and blade pressure.

Electrosurgical devices for applying electrical energy to tissue in order to treat and/or destroy the tissue are also finding increasingly widespread applications in surgical procedures. An electrosurgical device typically includes a hand piece, an instrument having a distally-mounted end effector (e.g., one or more electrodes). The end effector can be positioned against the tissue such that electrical current is introduced into the tissue. Electrosurgical devices can be configured for bipolar or monopolar operation. During bipolar operation, current is introduced into and returned from the tissue by active and return electrodes, respectively, of the end effector. During monopolar operation, current is introduced into the tissue by an active electrode of the end effector and returned through a return electrode (e.g., a grounding pad) separately located on a patient's body. Heat generated by the current flowing through the tissue may form hemostatic seals within the tissue and/or between tissues and thus may be particularly useful for sealing blood vessels, for example. The end effector of an electrosurgical device also may include a cutting member that is movable relative to the tissue and the electrodes to transect the tissue.

Electrical energy applied by an electrosurgical device can be transmitted to the instrument by a generator in communication with the hand piece. The electrical energy may be in the form of radio frequency (“RF”) energy. RF energy is a form of electrical energy that may be in the frequency range of 200 kilohertz (kHz) to 1 megahertz (MHz). In application, an electrosurgical device can transmit low frequency RF energy through tissue, which causes ionic agitation, or friction, in effect resistive heating, thereby increasing the temperature of the tissue. Because a sharp boundary is created between the affected tissue and the surrounding tissue, surgeons can operate with a high level of precision and control, without sacrificing un-targeted adjacent tissue. The low operating temperatures of RF energy is useful for removing, shrinking, or sculpting soft tissue while simultaneously sealing blood vessels. RF energy works particularly well on connective tissue, which is primarily comprised of collagen and shrinks when contacted by heat.

The RF energy may be in a frequency range described in EN 60601-2-2:2009+A11:2011, Definition 201.3.218—HIGH FREQUENCY. For example, the frequency in monopolar RF applications may be typically restricted to less than 5 MHz. However, in bipolar RF applications, the frequency can be almost anything. Frequencies above 200 kHz can be typically used for monopolar applications in order to avoid the unwanted stimulation of nerves and muscles that would result from the use of low frequency current. Lower frequencies may be used for bipolar applications if the risk analysis shows the possibility of neuromuscular stimulation has been mitigated to an acceptable level. Normally, frequencies above 5 MHz are not used in order to minimize the problems associated with high frequency leakage currents. Higher frequencies may, however, be used in the case of bipolar applications. It is generally recognized that 10 mA is the lower threshold of thermal effects on tissue.

A challenge of using these medical devices is the inability to control and customize the power output depending on the type of tissue being treated by the devices. It would be desirable to provide a surgical instrument that overcomes some of the deficiencies of current instruments. The surgical system described herein overcomes those deficiencies.

SUMMARY

In one aspect, a surgical instrument for coagulating and dissecting tissue is provided. The surgical instrument comprising a processor; an end effector at a distal end of the surgical instrument, the end effector configured to interact with tissue, the end effector comprising: a clamp arm; an ultrasonic blade; a force sensor in communication with the processor and configured to measure a force applied to tissue located between the clamp arm and the ultrasonic blade; and a temperature sensor in communication with the processor; an ultrasonic transducer acoustically coupled to the ultrasonic blade and configured to receive a drive signal from a generator to cause ultrasonic motion of the ultrasonic blade and deliver energy to the ultrasonic blade; wherein the processor is configured to: determine a type of tissue interacting with the end effector based on a tissue coefficient of friction, wherein the tissue coefficient of friction is determined based on the force applied to the tissue by the end effector, the ultrasonic motion of the ultrasonic blade, and a rate of heat generated by the end effector; and dynamically control the drive signal delivered to the ultrasonic transducer based on the type of tissue interacting with the end effector.

In one aspect, a method for detecting a short circuit in a surgical system configured to apply radio frequency energy and ultrasonic energy to a target surgical site is provided. The method comprises applying radio frequency (RF) energy with an end effector to the target surgical site; transitioning from applying the RF energy to applying ultrasonic energy with the end effector to the target surgical site; transmitting an exploratory ultrasonic pulse to the surgical site; measuring an ultrasonic property about the ultrasonic pulse upon transmission to the surgical site; determining whether the ultrasonic property is consistent with a behavior of low impedance tissue when ultrasonic energy is applied to the low impedance tissue; and continuing to apply ultrasonic energy to cut the low impedance tissue if it is determined that the ultrasonic property is consistent with ultrasonic energy being applied to low impedance tissue.

According to aspects of the present application, during tissue treatment, a parameterized tissue model can be fitted to the tissue. The parameters that are found in the model can be used to generate an optimal controller in real-time and could also be correlated to specific tissue characteristics. The present application provides real-time optimization on a generator control system based on RF impedance and real-time tissue evaluation.

According to aspects of the present application, methods of system identification may be used to model the tissue in real-time and develop controllers in real-time, specific to a particular tissue type to maximize sealing, minimize sticking of tissue, and cycle times. Furthermore, control of the output of a surgical instrument based on tissue characteristics and changes in tissue during sealing and cutting cycles is provided.

According to one aspect, a surgical instrument uses an RF energy modality to sense tissue characteristics, such as impedance, and the changes of the tissue characteristics to modulate the output power of an ultrasonic tissue treating system. Specifically, the output power of a surgical instrument may be modulated as a function of a desired impedance trajectory where the impedance trajectory results in a desired tissue effect or outcome. In one aspect, the RF output may be therapeutic, e.g. tissue treating, or sub-therapeutic, e.g. sensing only. The RF output may be applied to the tissue and the voltage and current, or representations of the voltage and current, are measured or estimated. The impedance may be calculated by determining the ratio of the voltage to the current.

In addition, RF impedance is known to change during the heating and coagulation of tissue. RF impedance can be used as an indicator of the state of the tissue and therefore can be used to indicate progress in a coagulation cycle, vessel sealing cycle, cutting etc. An extension of this change in RF impedance can be used to form a desired treatment cycle if the output is modulated such that the RF impedance follows a particular, desired course of change in impedance. The desired course of impedance can be pre-determined based on the instrument's operating parameters or determined by selection of the surgeon or measurement of tissue parameters to set this course of treatment. The course of impedance can determine one or more of the output power, output waveform or waveshape, selection of energy mode or modality or a point to terminate the application of energy to tissue.

In one aspect, a surgical energy generator system is disclosed, the system comprises an ultrasonic output stage configured to drive a transducer coupled to a tissue treating portion of a surgical instrument, where the tissue treating portion applies vibrational energy to tissue to affect treatment of that tissue and vibration amplitude of the tissue treating portion is controlled by a controller; an RF output stage configured to supply electrosurgical energy to the tissue via at least one electrode configured to apply electrosurgical energy to the tissue; sensing circuitry configured to measure impedance of the tissue; and a controller programmed to determine whether a tissue reaction has occurred as a function of impedance values and a predetermined rise in impedance, where the tissue reaction corresponds to a boiling point of tissue fluid, to generate a target impedance trajectory as a function of measured impedance and a predetermined desired rate of change of impedance based on the tissue reaction determination, where the target impedance trajectory includes a plurality of target impedance values for each of a plurality of timesteps, and to drive tissue impedance along the target impedance trajectory by adjusting the output level of the ultrasonic output stage to substantially match tissue impedance to a corresponding target impedance value for at least a predetermined minimum time period.

In one aspect, an apparatus is provided for dissecting and coagulating tissue. The apparatus comprises: a surgical instrument having an end effector configured to interact with a tissue at a distal end thereof; a generator electrically coupled to the surgical instrument and configured to deliver radio frequency (RF) energy and ultrasonic energy to the end effector to allow the end effector to interact with the tissue; wherein the energy delivered to the end effector switches between RF energy and ultrasonic energy based on a determination of a tissue impedance of the tissue interacting with the end effector such that the generator switches from RF energy to ultrasonic energy when the tissue impedance reaches a threshold level.

In addition to the foregoing, various other method and/or system and/or program product aspects are set forth and described in the teachings such as text (e.g., claims and/or detailed description) and/or drawings of the present disclosure.

The foregoing is a summary and thus may contain simplifications, generalizations, inclusions, and/or omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is NOT intended to be in any way limiting. Other aspects, features, and advantages of the devices and/or processes and/or other subject matter described herein will become apparent in the teachings set forth herein.

In one or more various aspects, related systems include but are not limited to circuitry and/or programming for effecting herein-referenced method aspects; the circuitry and/or programming can be virtually any combination of hardware, software, and/or firmware configured to affect the herein-referenced method aspects depending upon the design choices of the system designer. In addition to the foregoing, various other method and/or system aspects are set forth and described in the teachings such as text (e.g., claims and/or detailed description) and/or drawings of the present disclosure.

Further, it is understood that any one or more of the following-described forms, expressions of forms, examples, can be combined with any one or more of the other following-described forms, expressions of forms, and examples.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

FIGURES

The novel features of the described forms are set forth with particularity in the appended claims. The described forms, however, both as to organization and methods of operation, may be best understood by reference to the following description, taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates one aspect of a surgical system comprising a generator and various surgical instruments usable therewith;

FIG. 2 is a diagram of one aspect of the ultrasonic surgical instrument of FIG. 16;

FIG. 3 is a diagram of one aspect of the surgical system of FIG. 16;

FIG. 4 is a model illustrating one aspect of a motional branch current;

FIG. 5 is a structural view of one aspect of a generator architecture;

FIG. 6 illustrates one aspect of a drive system of a generator, which creates the ultrasonic electrical signal for driving an ultrasonic transducer;

FIG. 7 illustrates one aspect of a drive system of a generator comprising a tissue impedance module;

FIG. 8 illustrates one aspect of a generator for delivering multiple energy modalities to a surgical instrument;

FIG. 9 is an example graph of two waveforms of energy from one aspect of a generator;

FIG. 10 is an example graph of the sum of the waveforms of FIG. 9;

FIG. 11 is an example graph of sum of the waveforms of FIG. 9 with the RF waveform dependent on the ultrasonic waveform;

FIG. 12 is an example graph of the sum of the waveforms of FIG. 9 with the RF waveform being a function of the ultrasonic waveform;

FIG. 13 is an example graph of a complex RF waveform;

FIG. 14 illustrates one aspect of an end effector comprising RF data sensors located on the clamp arm;

FIG. 15 illustrates one aspect of the flexible circuit shown in FIG. 14 in which the sensors may be mounted to or formed integrally therewith;

FIG. 16 is a cross-sectional view of the flexible circuit shown in FIG. 15;

FIG. 17 illustrates one aspect of a segmented flexible circuit configured to fixedly attach to a clamp arm of an end effector;

FIG. 18 illustrates one aspect of a segmented flexible circuit configured to mount to a clamp arm of an end effector;

FIG. 19 illustrates one aspect of an end effector configured to measure a tissue gap G_(T);

FIG. 20 illustrates one aspect of a left-right segmented flexible circuit;

FIG. 21 illustrates one aspect of an end effector comprising segmented flexible circuit as shown in FIG. 20;

FIG. 22 illustrates the end effector shown in FIG. 21 with the clamp arm clamping tissue between the clamp arm and the ultrasonic blade;

FIG. 23 illustrates graphs of energy applied by the right and left side of an end effector based on locally sensed tissue parameters;

FIG. 24 illustrates a graph depicting one aspect of adjustment of threshold due to the measurement of a secondary tissue parameter such as continuity, temperature, pressure, and the like;

FIG. 25 is a cross-sectional view of one aspect of a flexible circuit comprising RF electrodes and data sensors embedded therein;

FIG. 26 is a cross-sectional view of one aspect of an end effector configured to sense force or pressure applied to tissue located between a clamp arm and an ultrasonic blade;

FIG. 27 is a schematic diagram of one aspect of a signal layer of a flexible circuit;

FIG. 28 is a schematic diagram of sensor wiring for the flexible circuit shown in FIG. 27;

FIG. 29 is a schematic diagram of one aspect of an RF energy drive circuit;

FIG. 30 is a graphical representation of measuring tissue gap at a preset time;

FIG. 31 is a time to preset force versus time graph for thin, medium, and thick tissue types;

FIG. 32 is a graphical depiction of a graph of three curves, where the first curve represents power (P), voltage (V_(RF)), and current (I_(RF)) versus tissue impedance (Z), the second curve and third curve represent tissue impedance (Z) versus time (t);

FIG. 33 is a plan view of one aspect of an end effector;

FIG. 34 is a side view of the end effector shown in FIG. 33 with a partial cut away view to expose the underlying structure of the clamp arm and an ultrasonic blade;

FIG. 35 is partial sectional view of the end effector shown in FIGS. 33, 34 to expose the ultrasonic blade and right and left electrodes, respectively;

FIG. 36 is a cross-sectional view taken at section 36-36 of the end effector shown in FIG. 33;

FIG. 37 is cross-sectional view taken at section 37-37 of the end effector shown in FIG. 33;

FIG. 38 is a cross-sectional view taken at section 36-36 of the end effector shown in FIG. 33, except that the ultrasonic blade has a different geometric configuration;

FIG. 39 is cross-sectional view taken at section 37-37 of the end effector shown in FIG. 33, except that the ultrasonic blade has a different geometric configuration;

FIG. 40 is a cross-sectional view taken at section 36-36 of the end effector shown in FIG. 33, except that the ultrasonic blade has a different geometric configuration;

FIG. 41 is cross-sectional view taken at section 37-37 of the end effector shown in FIG. 33, except that the ultrasonic blade has a different geometric configuration;

FIG. 42A is a graphical representation of one aspect of a medical device surrounding tissue;

FIG. 42B is a graphical representation of one aspect of a medical device compressing tissue;

FIG. 43A is a graphical representation of one aspect of a medical device compressing tissue;

FIG. 43B also depicts example forces exerted by one aspect of an end-effector of a medical device compressing tissue;

FIG. 44 illustrates a logic diagram of one aspect of a feedback system;

FIG. 45 is a graph of power versus force as measured with a plurality of plot points for various tissue types;

FIG. 46 is another graph of power versus force as measured with a plurality of plot points for various tissue types;

FIG. 47 is a logic flow diagram of one aspect of dynamically changing the energy delivered to a surgical instrument based on a determination of tissue type being treated by the instrument;

FIG. 48 is a logic flow diagram of one aspect of dynamically changing the energy delivered to a surgical instrument based on a determination of tissue type being treated by the instrument;

FIG. 49 is a logic flow diagram of one aspect of a method of dynamically changing the energy delivered to a surgical instrument based on a determination of the hydration level of tissue being treated by a surgical instrument;

FIG. 50 is a logic flow diagram of one aspect of a method of dynamically changing energy being delivered from a generator based on the type of tissue being treated by a surgical instrument and various characteristics of the tissue;

FIG. 51 is a logic flow diagram of one aspect of a technique for dynamically changing the energy delivered from a generator based on aperture defined by the end effector and energy parameters;

FIG. 52 is a logic flow diagram of one aspect of a technique for dynamically changing the energy delivered from a generator based on aperture defined by the end effector and energy parameters;

FIG. 53 is a logic flow diagram of one aspect of a dynamic tissue sensing technique;

FIG. 54 is a logic flow diagram of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles;

FIG. 55 is a logic flow diagram of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles by dynamically changing energy being delivered from the generator during the treatment of the tissue based on the changing aperture defined by the end effector;

FIG. 56 is a logic flow diagram of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles by dynamically communicating energy parameters to the generator during the treatment of the tissue based on the changing aperture defined by the end effector of the surgical instrument;

FIG. 57 is a logic flow diagram of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements and the aperture defined by the clamp jaw measurements;

FIG. 58 is a logic flow diagram of one aspect of a method of dynamically changing the energy delivered to a surgical instrument based on a determination of a state of coagulation of tissue being treated by the surgical instrument;

FIG. 59 is a logic flow diagram of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements;

FIG. 60 is a logic flow diagram of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements and the aperture defined by the clamp jaw measurements;

FIG. 61 is a logic flow diagram of a technique for distinguishing a short circuit from low impedance tissue while utilizing RF energy by measuring voltage properties of an exploratory ultrasonic pulse;

FIG. 62 is a logic flow diagram of a technique for distinguishing a short circuit from low impedance tissue while delivering RF energy and measuring acoustic properties of an exploratory ultrasonic pulse, according to some aspects;

FIG. 63 is a logic flow diagram of a technique for conducting a tissue sealing technique without cutting by using a combination of ultrasonic energy and RF energy, according to some aspects;

FIG. 64 is a logic flow diagram of a technique for conducting a tissue sealing technique without cutting by using a combination of ultrasonic energy and RF energy, according to some aspects;

FIG. 65 is logic flow diagram of a technique for detecting low impedance tissue or metal shorts that may cause false short circuits in RF mode;

FIG. 66 is a timing diagram of a seal only pulse sequence illustrating a basic configuration of pulsing RF and ultrasonic energy for “Seal Only” mode;

FIG. 67 is a timing diagram of a seal only pulse sequence illustrating a basic configuration of pulsing RF and ultrasonic energy for “Seal Only” mode;

FIG. 68 is a timing diagram of a seal only pulse sequence;

FIG. 69 is a timing diagram of a seal only pulse sequence;

FIG. 70 is a timing diagram of a seal and cut pulse sequence, which begins and ends with ultrasonic energy pulses delivered at the same amplitude during the sealing a cutting cycles;

FIG. 71 is a timing diagram of a seal and cut pulse sequence, which begins and ends with ultrasonic energy pulses delivered at variable amplitude during the sealing a cutting cycles;

FIG. 72 is a timing diagram of a seal only pulse sequence where the ultrasonic energy pulse current is be set based on the impedance measured with the preceding RF energy pulse;

FIG. 73 is a logic flow diagram of a technique for delivering pulses of different energy modalities to tissue;

FIG. 74 is a logic flow diagram of a technique for delivering pulses of different energy modalities to tissue;

FIG. 75 is a logic flow diagram of a technique for delivering pulses of different energy modalities to tissue;

FIG. 76 is a logic flow diagram of one aspect of a process of applying simultaneous activation of different energy modalities to tissue;

FIG. 77 is a graphical representation of RF Impedance versus Time in connection with the logic flow diagram of FIG. 67 to illustrate the ultrasonic termination impedance;

FIG. 78 illustrates an example of the quality of a seal made in a vessel using the simultaneous activation of RF and ultrasonic energy modalities as described in connection with FIGS. 76 and 77;

FIG. 79 is a graphical representation of seal burst pressure of carotid bundles versus an RF only seal and a simultaneous RF/ultrasonic seal as described in connection with FIGS. 76-78;

FIG. 80 is a logic flow diagram of a process of simultaneous activation of RF and ultrasonic energy modalities;

FIG. 81 is a block diagram of one aspect describing the selection and application of composite load curves in a tissue seal control process;

FIG. 82 illustrates one aspect of a neural network for controlling a generator;

FIG. 83 is an example graph showing RF impedance versus time of tissue impedance at which a proper tissue seal is achieved using RF energy;

FIG. 84 is a graphical representation of RF impedance versus time of tissue impedance with 40 W of RF power delivered to tissue using a downhill simplex technique for a model of tissue and experimental data;

FIG. 85 is a graphical representation of RF impedance versus time of tissue impedance using a linear quadratic controller (LQR) with precompensation to achieve steady state at a tissue impedance equal to 250 Ohms for a model of tissue and experimental data;

FIG. 86 is a graphical representation of RF impedance versus time of tissue impedance using a linear quadratic controller (LQR) with precompensation to achieve steady state at a tissue impedance that rises at a rate of 50 Ohms/second for a model of tissue and experimental data;

FIG. 87 is a logic flow diagram of a method for identifying a tissue type and developing a control process to control the application of an energy modality to the tissue according to tissue impedance;

FIG. 88 is a logic flow diagram of a method for treating tissue based on tissue impedance according to one aspect of the present disclosure;

FIG. 89 is a graphical depiction of a tissue impedance function represented as tissue impedance |Z| (Ohms) as a function of time (Sec) showing one aspect of a termination impedance at which a proper tissue seal is achieved utilizing RF energy;

FIG. 90 is a logic flow diagram of one aspect of a method of dynamically changing the energy delivered to a surgical instrument based on a determination of a tissue impedance of tissue being treated by a surgical instrument;

FIG. 91A is a graphical depiction of power and impedance as a function of time delivered from a generator to an end effector of a surgical instrument;

FIG. 91B is a graphical depiction of voltage and current as a function of time delivered from a generator to an end effector of a surgical instrument;

FIG. 91C is a graphical depiction of power, impedance, voltage, and current as a function of time delivered from a generator to an end effector of a surgical instrument as shown in FIGS. 91A and 91B;

FIG. 92 is a logic flow diagram of one aspect of a process of applying simultaneous activation of different energy modalities to tissue;

FIG. 93 is a graphical depiction of an RF tissue impedance function represented as RF tissue impedance (Ohms) as a function of time (Sec) in connection with the logic flow diagram of FIG. 92 to illustrate the ultrasonic and RF termination impedance;

FIG. 94 illustrates an example of the quality of a seal made in a vessel utilizing simultaneous activation of RF and ultrasonic energy modalities as described in connection with FIGS. 92 and 93;

FIG. 95 is a boxplot graphic comparison of the burst pressure of a carotid artery seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94;

FIG. 96 is a boxplot graphic comparison of the burst pressure of a carotid artery bundle seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94;

FIG. 97 is a boxplot graphic comparison of the burst pressure of a thyrocervical artery seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94;

FIG. 98 is a boxplot graphic comparison of the burst pressure of a carotid artery bundle seal made utilizing simultaneous application of: (1) RF and lower ultrasonic energy and (2) RF energy and higher ultrasonic energy as described in connection with FIGS. 92-94;

FIG. 99 is a boxplot graphic comparison of the burst pressure of a carotid artery bundle seal made utilizing simultaneous application of RF and ultrasonic energy at different termination impedances as described in connection with FIGS. 92-94;

FIG. 100 is an example of a vessel with a partial seal made utilizing simultaneous application of RF and ultrasonic energy and a partial transection made utilizing ultrasonic energy;

FIG. 101 is a graphical depiction of an RF tissue impedance function represented as RF tissue impedance (Ohms) as a function of time (Sec) and an ultrasonic current function represented as ultrasonic current (mA) as a function of time (Sec) during a “seal only” modality;

FIG. 102 is logic flow diagram of one aspect of a technique for simultaneous activation of RF and ultrasonic energy and modulating the ultrasonic energy to achieve a seal only process;

FIG. 103 is a graphical depiction of an RF tissue impedance function represented as RF tissue impedance (Ohms) as a function of time (Sec) and an ultrasonic current function represented as ultrasonic current (mA) as a function of time (Sec) during a “seal and cut” modality;

FIG. 104 is logic flow diagram of one aspect of a technique for simultaneous activation of RF and ultrasonic energy and modulating the ultrasonic energy to achieve a seal and cut process;

FIG. 105A is a graphical depiction of an ultrasonic current functions represented as ultrasonic current I_(h) (Amperes) delivered to the ultrasonic transducer as a function of RF tissue impedance Z (Ohms) for various n values;

FIG. 105B is a graphical depiction of an ultrasonic current functions represented as ultrasonic current I_(h) (Amperes) delivered to the ultrasonic transducer as a function of RF tissue impedance Z (Ohms) for various n values;

FIG. 106 is a graphical depiction of multiple ultrasonic functions represented as functions of time; and

FIG. 107 is a graphical depiction of constant RF power that was inputted into Equation 9 with RF energy terminated at 500 Ohm terminal impedance.

DESCRIPTION

Before explaining various forms of surgical instruments in detail, it should be noted that the illustrative forms are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative forms may be implemented or incorporated in other forms, variations and modifications, and may be practiced or carried out in various ways. Further, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative forms for the convenience of the reader and are not for the purpose of limitation thereof.

Further, it is understood that any one or more of the following-described forms, expressions of forms, examples, can be combined with any one or more of the other following-described forms, expressions of forms, and examples.

Various forms are directed to improved ultrasonic and/or electrosurgical (RF) instruments configured for effecting tissue dissecting, cutting, and/or coagulation during surgical procedures. In one form, a combined ultrasonic and electrosurgical instrument may be configured for use in open surgical procedures, but has applications in other types of surgery, such as laparoscopic, endoscopic, and robotic-assisted procedures. Versatile use is facilitated by selective use of ultrasonic and RF energy.

The various forms will be described in combination with an ultrasonic instrument as described herein. Such description is provided by way of example, and not limitation, and is not intended to limit the scope and applications thereof. For example, any one of the described forms is useful in combination with a multitude of ultrasonic instruments including those described in, for example, U.S. Pat. Nos. 5,938,633; 5,935,144; 5,944,737; 5,322,055; 5,630,420; and 5,449,370.

As will become apparent from the following description, it is contemplated that forms of the surgical instruments described herein may be used in association with an oscillator unit of a surgical system, whereby ultrasonic energy from the oscillator unit provides the desired ultrasonic actuation for the present surgical instrument. It is also contemplated that forms of the surgical instrument described herein may be used in association with a signal generator unit of a surgical system, whereby electrical energy in the form of radio frequencies (RF), for example, is used to provide feedback to the user regarding the surgical instrument. The ultrasonic oscillator and/or the signal generator unit may be non-detachably integrated with the surgical instrument or may be provided as separate components, which can be electrically attachable to the surgical instrument.

One form of the present surgical apparatus is particularly configured for disposable use by virtue of its straightforward construction. However, it is also contemplated that other forms of the present surgical instrument can be configured for non-disposable or multiple uses. Detachable connection of the present surgical instrument with an associated oscillator and signal generator unit is presently disclosed for single-patient use for illustrative purposes only. However, non-detachable integrated connection of the present surgical instrument with an associated oscillator and/or signal generator unit is also contemplated. Accordingly, various forms of the presently described surgical instruments may be configured for single use and/or multiple use with either detachable and/or non-detachable integral oscillator and/or signal generator unit, without limitation, and all combinations of such configurations are contemplated to be within the scope of the present disclosure.

The surgical instruments disclosed herein are related to surgical instruments described in the following commonly owned applications and filed concurrently herewith: END7747USNP1 titled “Surgical System Wth User Adaptable Techniques” by Stulen et al., END7747USNP2 titled “Surgical System With User Adaptable Techniques Employing Multiple Energy Modalities Based On Tissue Parameters” by Wiener et al., END7747USNP3 titled “Surgical System With User Adaptable Techniques Based On Tissue Impedance” by Yates et al., and END7747USNP4 titled “Surgical System With User Adaptable Techniques Employing Simultaneous Energy Modalities Based On Tissue Parameters” by Yates et al., each of which is incorporated herein by reference in its entirety.

With reference to FIGS. 1-5, one form of a surgical system 10 including an ultrasonic surgical instrument is illustrated. FIG. 1 illustrates one form of a surgical system 100 comprising a generator 102 and various surgical instruments 104, 106, 108 usable therewith. FIG. 2 is a diagram of the ultrasonic surgical instrument 104 of FIG. 1.

FIG. 1 illustrates a generator 102 configured to drive multiple surgical instruments 104, 106, 108. The first surgical instrument 104 comprises a handpiece 105, an ultrasonic transducer 120, a shaft 126, and an end effector 122. The end effector 122 comprises an ultrasonic blade 128 acoustically coupled to the transducer 120 and a clamp arm 140. The handpiece 105 comprises a trigger 143 to operate the clamp arm 140 and a combination of the toggle buttons 134 a, 134 b, 134 c to energize and drive the ultrasonic blade 128 or other function. The toggle buttons 134 a, 134 b, 134 c can be configured to energize the ultrasonic transducer 120 with the generator 102.

Still with reference to FIG. 1, the generator 102 also is configured to drive a second surgical instrument 106. The second surgical instrument 106 is an RF electrosurgical instrument and comprises a handpiece 107, a shaft 127, and an end effector 124. The end effector 124 comprises electrodes in the clamp arms 143 and return through the ultrasonic blade 149. The electrodes are coupled to and energized by a bipolar energy source within the generator 102. The handpiece 107 comprises a trigger 147 to operate the clamp arm 145 and an energy button 135 to actuate an energy switch to energize the electrodes in the end effector 124.

Still with reference to FIG. 1, the generator 102 also is configures to drive a combination electrosurgical and ultrasonic instrument 108. The combination electrosurgical and ultrasonic multifunction surgical instrument 108 comprises a handpiece 109, a shaft 129, and an end effector 125. The end effector comprises an ultrasonic blade 149 and a clamp arm 145. The ultrasonic blade 149 is acoustically coupled to the ultrasonic transducer 120. The handpiece 109 comprises a trigger 147 to operate the clamp arm 145 and a combination of the toggle buttons 137 a, 137 b, 137 c to energize and drive the ultrasonic blade 149 or other function. The toggle buttons 137 a, 137 b, 137 c can be configured to energize the ultrasonic transducer 120 with the generator 102 and energize the ultrasonic blade 149 with a bipolar energy source also contained within the generator 102.

Wth reference to both FIGS. 1 and 2, the generator 102 is configurable for use with a variety of surgical devices. According to various forms, the generator 102 may be configurable for use with different surgical devices of different types including, for example, the ultrasonic surgical instrument 104, the electrosurgical or RF surgical devices, such as, the RF electrosurgical instrument 106, and the multifunction surgical instrument 108 that integrate electrosurgical RF and ultrasonic energies delivered simultaneously from the generator 102. Although in the form of FIG. 1, the generator 102 is shown separate from the surgical instruments 104, 106, 108, in one form, the generator 102 may be formed integrally with either of the surgical instrument 104, 106, 108 to form a unitary surgical system. The generator 102 comprises an input device 110 located on a front panel of the generator 102 console. The input device 110 may comprise any suitable device that generates signals suitable for programming the operation of the generator 102. The generator 102 also may comprise one or more output devices 112.

The generator 102 is coupled to an ultrasonic transducer 120 via a cable 144. The ultrasonic transducer 120 and a waveguide extending through a shaft 126 (waveguide not shown in FIG. 2) may collectively form an ultrasonic drive system driving an ultrasonic blade 128 of an end effector 122. The end effector 122 further may comprise a clamp arm 140 to clamp tissue between the clamp arm 140 and the ultrasonic blade 128. In one form, the generator 102 may be configured to produce a drive signal of a particular voltage, current, and/or frequency output signal that can be stepped or otherwise modified with high resolution, accuracy, and repeatability.

Still with reference to FIG. 2, It will be appreciated that a surgical instrument 104 may comprise any combination of the toggle buttons 134 a, 134 b, 134 c. For example, the surgical instrument 104 could be configured to have only two toggle buttons: a toggle button 134 a for producing maximum ultrasonic energy output and a toggle button 134 c for producing a pulsed output at either the maximum or less than maximum power level. In this way, the drive signal output configuration of the generator 102 could be 5 continuous signals and 5 or 4 or 3 or 2 or 1 pulsed signals. In certain forms, the specific drive signal configuration may be controlled based upon, for example, EEPROM settings in the generator 102 and/or user power level selection(s).

In certain forms, a two-position switch may be provided as an alternative to a toggle button 134 c. For example, a surgical instrument 104 may include a toggle button 134 a for producing a continuous output at a maximum power level and a two-position toggle button 134 b. In a first detented position, toggle button 134 b may produce a continuous output at a less than maximum power level, and in a second detented position the toggle button 134 b may produce a pulsed output (e.g., at either a maximum or less than maximum power level, depending upon the EEPROM settings).

Still with reference to FIG. 2, forms of the generator 102 may enable communication with instrument-based data circuits. For example, the generator 102 may be configured to communicate with a first data circuit 136 and/or a second data circuit 138. For example, the first data circuit 136 may indicate a burn-in frequency slope, as described herein. Additionally or alternatively, any type of information may be communicated to second data circuit for storage therein via a data circuit interface (e.g., using a logic device). Such information may comprise, for example, an updated number of operations in which the instrument has been used and/or dates and/or times of its usage. In certain forms, the second data circuit may transmit data acquired by one or more sensors (e.g., an instrument-based temperature sensor). In certain forms, the second data circuit may receive data from the generator 102 and provide an indication to a user (e.g., an LED indication or other visible indication) based on the received data. The second data circuit 138 contained in the multifunction surgical instrument 108 of a surgical device. In some forms, the second data circuit 138 may be implemented in a many similar to that of the first data circuit 136 described herein. An instrument interface circuit may comprise a second data circuit interface to enable this communication. In one form, the second data circuit interface may comprise a tri-state digital interface, although other interfaces also may be used. In certain forms, the second data circuit may generally be any circuit for transmitting and/or receiving data. In one form, for example, the second data circuit may store information pertaining to the particular surgical instrument with which it is associated. Such information may include, for example, a model number, a serial number, a number of operations in which the surgical instrument has been used, and/or any other type of information. In some forms, the second data circuit 138 may store information about the electrical and/or ultrasonic properties of an associated transducer 120, end effector 122, or ultrasonic drive system. Various processes and techniques described herein may be executed by a generator. It will be appreciated, however, that in certain example forms, all or a part of these processes and techniques may be performed by internal logic 139 of the multifunction surgical instrument 108.

FIG. 3 is a diagram of the surgical system 100 of FIG. 1. In various forms, the generator 102 may comprise several separate functional elements, such as modules and/or blocks. Different functional elements or modules may be configured for driving the different kinds of surgical instruments 104, 106, 108. For example, an ultrasonic generator drive circuit 114 may drive ultrasonic devices such as the ultrasonic surgical instrument 104 via a cable 142. An electrosurgery/RF generator drive circuit 116 may drive the electrosurgical instrument 106 via a cable 144. For example, the respective drive circuits 114, 116 may generate respective drive signals for driving the surgical instruments 104, 106, 108. In various forms, the ultrasonic generator drive circuit 114 (e.g., ultrasonic drive circuit) and/or the electrosurgery/RF generator drive circuit 116 (e.g., RF drive circuit) each may be formed integrally with the generator 102. Alternatively, one or more of the drive circuits 114, 116 may be provided as a separate circuit module electrically coupled to the generator 102. (The drive circuits 114 and 116 are shown in phantom to illustrate this option.) Also, in some forms, the electrosurgery/RF generator drive circuit 116 may be formed integrally with the ultrasonic generator drive circuit 114, or vice versa. Also, in some forms, the generator 102 may be omitted entirely and the drive circuits 114, 116 may be executed by processors or other hardware within the respective surgical instruments 104, 106, 108.

In other forms, the electrical outputs of the ultrasonic generator drive circuit 114 and the electrosurgery/RF generator drive circuit 116 may be combined into a single drive circuit to provide a single electrical signal capable of driving the multifunction surgical instrument 108 simultaneously with electrosurgical RF and ultrasonic energies via a cable 146. The multifunction surgical instrument 108 comprises an ultrasonic transducer 120 coupled to an ultrasonic blade 149 and one or more electrodes in the end effector 124 to receive electrosurgical RF energy. In such implementations, the combined RF/ultrasonic signal is coupled to the multifunction surgical instrument 108. The multifunction surgical instrument 108 comprises signal processing components to split the combined RF/ultrasonic signal such that the RF signal can be delivered to the electrodes in the end effector 124 and the ultrasonic signal can be delivered to the ultrasonic transducer 120.

In accordance with the described forms, the ultrasonic generator drive circuit 114 may produce a drive signal or signals of particular voltages, currents, and frequencies, e.g., 55,500 cycles per second (Hz). The drive signal or signals may be provided to the ultrasonic surgical instrument 104, and specifically to the transducer 120, which may operate, for example, as described herein. The transducer 120 and a waveguide extending through the shaft 126 (waveguide not shown in FIG. 2) may collectively form an ultrasonic drive system driving an ultrasonic blade 128 of an end effector 122. In one form, the generator 102 may be configured to produce a drive signal of a particular voltage, current, and/or frequency output signal that can be stepped or otherwise modified with high resolution, accuracy, and repeatability.

The generator 102 may be activated to provide the drive signal to the transducer 120 in any suitable manner. For example, the generator 102 may comprise a foot switch 130 coupled to the generator 102 via a foot switch cable 132. A clinician may activate the transducer 120 by depressing the foot switch 130. In addition, or instead of the foot switch 130 some forms of the ultrasonic surgical instrument 104 may utilize one or more switches positioned on the hand piece that, when activated, may cause the generator 102 to activate the transducer 120. In one form, for example, the one or more switches may comprise a pair of toggle buttons 134 a, 134 b (FIG. 2), for example, to determine an operating mode of the surgical instrument 104. When the toggle button 134 a is depressed, for example, the ultrasonic generator 102 may provide a maximum drive signal to the transducer 120, causing it to produce maximum ultrasonic energy output. Depressing toggle button 134 b may cause the ultrasonic generator 102 to provide a user-selectable drive signal to the transducer 120, causing it to produce less than the maximum ultrasonic energy output. The surgical instrument 104 additionally or alternatively may comprise a second switch (not shown) to, for example, indicate a position of a jaw closure trigger for operating jaws of the end effector 122. Also, in some forms, the ultrasonic generator 102 may be activated based on the position of the jaw closure trigger, (e.g., as the clinician depresses the jaw closure trigger to close the jaws, ultrasonic energy may be applied).

Additionally or alternatively, the one or more switches may comprises a toggle button 134 c that, when depressed, causes the generator 102 to provide a pulsed output. The pulses may be provided at any suitable frequency and grouping, for example. In certain forms, the power level of the pulses may be the power levels associated with toggle buttons 134 a, 134 b (maximum, less than maximum), for example.

In accordance with the described forms, the electrosurgery/RF generator drive circuit 116 may generate a drive signal or signals with output power sufficient to perform bipolar electrosurgery using radio frequency (RF) energy. In bipolar electrosurgery applications, the drive signal may be provided, for example, to electrodes of the electrosurgical instrument 106, for example. Accordingly, the generator 102 may be configured for therapeutic purposes by applying electrical energy to the tissue sufficient for treating the tissue (e.g., coagulation, cauterization, tissue welding).

The generator 102 may comprise an input device 110 (FIG. 1) located, for example, on a front panel of the generator 102 console. The input device 110 may comprise any suitable device that generates signals suitable for programming the operation of the generator 102. In operation, the user can program or otherwise control operation of the generator 102 using the input device 110. The input device 110 may comprise any suitable device that generates signals that can be used by the generator (e.g., by one or more processors contained in the generator) to control the operation of the generator 102 (e.g., operation of the ultrasonic generator drive circuit 114 and/or electrosurgery/RF generator drive circuit 116). In various forms, the input device 110 includes one or more of buttons, switches, thumbwheels, keyboard, keypad, touch screen monitor, pointing device, remote connection to a general purpose or dedicated computer. In other forms, the input device 110 may comprise a suitable user interface, such as one or more user interface screens displayed on a touch screen monitor, for example. Accordingly, by way of the input device 110, the user can set or program various operating parameters of the generator, such as, for example, current (I), voltage (V), frequency (f), and/or period (T) of a drive signal or signals generated by the ultrasonic generator drive circuit 114 and/or electrosurgery/RF generator drive circuit 116.

The generator 102 also may comprise an output device 112 (FIGS. 1, 3), such as an output indicator, located, for example, on a front panel of the generator 102 console. The output device 112 includes one or more devices for providing a sensory feedback to a user. Such devices may comprise, for example, visual feedback devices (e.g., a visual feedback device may comprise incandescent lamps, light emitting diodes (LEDs), graphical user interface, display, analog indicator, digital indicator, bar graph display, digital alphanumeric display, LCD display screen, LED indicators), audio feedback devices (e.g., an audio feedback device may comprise speaker, buzzer, audible, computer generated tone, computerized speech, voice user interface (VUI) to interact with computers through a voice/speech platform), or tactile feedback devices (e.g., a tactile feedback device comprises any type of vibratory feedback, haptic actuator).

Although certain modules, circuits, and/or blocks of the generator 102 may be described by way of example, it can be appreciated that a greater or lesser number of modules, circuits, and/or blocks may be used and still fall within the scope of the forms. Further, although various forms may be described in terms of modules, circuits, and/or blocks to facilitate description, such modules, circuits, and/or blocks may be implemented by one or more hardware components, e.g., processors, Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs), Application Specific Integrated Circuits (ASICs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components. Also, in some forms, the various modules described herein may be implemented utilizing similar hardware positioned within the surgical instruments 104, 106, 108 (i.e., the generator 102 may be omitted).

In one form, the ultrasonic generator drive circuit 114 and electrosurgery/RF drive circuit 116 may comprise one or more embedded applications implemented as firmware, software, hardware, or any combination thereof. The drive circuits 114, 116 may comprise various executable modules such as software, programs, data, drivers, application program interfaces (APIs), and so forth. The firmware may be stored in nonvolatile memory (NVM), such as in bit-masked read-only memory (ROM) or flash memory. In various implementations, storing the firmware in ROM may preserve flash memory. The NVM may comprise other types of memory including, for example, programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or battery backed random-access memory (RAM) such as dynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronous DRAM (SDRAM).

In one form, the drive circuits 114, 116 comprise a hardware component implemented as a processor for executing program instructions for monitoring various measurable characteristics of the surgical instruments 104, 106, 108 and generating a corresponding output control signals for operating the surgical instruments 104, 106, 108. In forms in which the generator 102 is used in conjunction with the surgical instrument 104, the output control signal may drive the ultrasonic transducer 120 in cutting and/or coagulation operating modes. Electrical characteristics of the surgical instrument 104 and/or tissue may be measured and used to control operational aspects of the generator 102 and/or provided as feedback to the user. In forms in which the generator 102 is used in conjunction with the electrosurgical instrument 106, the output control signal may supply electrical energy (e.g., RF energy) to the end effector 124 in cutting, coagulation and/or desiccation modes. Electrical characteristics of the electrosurgical instrument 106 and/or tissue may be measured and used to control operational aspects of the generator 102 and/or provide feedback to the user. In various forms, as previously discussed, the hardware component may be implemented as a DSP, PLD, ASIC, circuits, and/or registers. In one form, the processor may be configured to store and execute computer software program instructions to generate the output signal functions for driving various components of the surgical instruments 104, 106, 108, such as the ultrasonic transducer 120 and the end effectors 122, 124.

FIG. 4 illustrates an equivalent circuit 150 of an ultrasonic transducer, such as the ultrasonic transducer 120 shown in FIGS. 1-3, according to one form. The circuit 150 comprises a first “motional” branch having a serially connected inductance L_(s), resistance R_(s) and capacitance C_(s) that define the electromechanical properties of the resonator, and a second capacitive branch having a static capacitance C_(o). Drive current I_(g) may be received from a generator at a drive voltage V_(g), with motional current I_(m) flowing through the first branch and current I_(g)-I_(m) flowing through the capacitive branch. Control of the electromechanical properties of the ultrasonic transducer may be achieved by suitably controlling I_(g) and V_(g). As explained above, conventional generator architectures may include a tuning inductor L_(t) (shown in phantom in FIG. 4) for tuning out in a parallel resonance circuit the static capacitance Co at a resonant frequency so that substantially all of generator's current output I_(g) flows through the motional branch. In this way, control of the motional branch current I_(m) is achieved by controlling the generator current output I_(g). The tuning inductor L_(t) is specific to the static capacitance C_(o) of an ultrasonic transducer, however, and a different ultrasonic transducer having a different static capacitance requires a different tuning inductor L_(t). Moreover, because the tuning inductor L_(t) is matched to the nominal value of the static capacitance Co at a resonant frequency, accurate control of the motional branch current I_(m) is assured only at that frequency, and as frequency shifts down with transducer temperature, accurate control of the motional branch current is compromised.

Forms of the generator 102 shown in FIGS. 1-3 do not rely on a tuning inductor L_(t) to monitor the motional branch current I_(m). Instead, the generator 102 may use the measured value of the static capacitance C_(o) in between applications of power for a specific ultrasonic surgical instrument 104 (along with drive signal voltage and current feedback data) to determine values of the motional branch current I_(m) on a dynamic and ongoing basis (e.g., in real-time). Such forms of the generator 102 are therefore able to provide virtual tuning to simulate a system that is tuned or resonant with any value of static capacitance C_(o) at any frequency, and not just at the resonant frequency dictated by a nominal value of the static capacitance C_(o).

FIG. 5 is a simplified block diagram of a generator 200 which is one form of the generator 102 shown in FIGS. 1-3 for proving inductorless tuning as described herein, among other benefits. Additional details of the generator 102 are described in commonly assigned and contemporaneously filed U.S. patent application Ser. No. 12/896,360, titled “Surgical Generator For Ultrasonic And Electrosurgical Devices,” Attorney Docket Number END6673USNP/100558, the disclosure of which is incorporated herein by reference in its entirety. Wth reference to FIG. 5, the generator 200 may comprise a patient isolated stage 202 in communication with a non-isolated stage 204 via a power transformer 206. A secondary winding 208 of the power transformer 206 is contained in the isolated stage 202 and may comprise a tapped configuration (e.g., a center-tapped or a non-center-tapped configuration) to define drive signal outputs 210 a, 210 b, 210 c for outputting drive signals to different surgical devices, such as, for example, an ultrasonic surgical instrument 104 and an electrosurgical instrument 106 (as shown in FIGS. 1-3). In particular, the drive signal outputs 210 a, 210 c may output an ultrasonic drive signal (e.g., a 420V RMS drive signal) to an ultrasonic surgical instrument 104, and the drive signal outputs 210 b, 210 c may output an electrosurgical RF drive signal (e.g., a 100V RMS drive signal) to an electrosurgical instrument 106, with the output 210 b corresponding to the center tap of the power transformer 206.

In certain forms, the ultrasonic and electrosurgical drive signals may be provided simultaneously to distinct surgical instruments and/or to a single surgical instrument having the capability to deliver both ultrasonic and electrosurgical energy to tissue, such as multifunction surgical instrument 108 (FIGS. 1 and 3). It will be appreciated that the electrosurgical signal, provided either to a dedicated electrosurgical instrument and/or to a combined multifunction ultrasonic/electrosurgical instrument may be either a therapeutic or sub-therapeutic level signal. For example, the ultrasonic and radio frequency signals can be delivered separately or simultaneously from a generator with a single output port in order to provide the desired output signal to the surgical instrument, as will be discussed in more detail below. Accordingly, the generator can combine the ultrasonic and electrosurgical RF energies and deliver the combined energies to the multifunction ultrasonic/electrosurgical instrument. Bipolar electrodes can be placed on one or both jaws of the end effector. One jaw may be driven by ultrasonic energy in addition to electrosurgical RF energy, working simultaneously. The ultrasonic energy may be employed to dissect tissue while the electrosurgical RF energy may be employed for vessel sealing.

The non-isolated stage 204 may comprise a power amplifier 212 having an output connected to a primary winding 214 of the power transformer 206. In certain forms the power amplifier 212 may be comprise a push-pull amplifier. For example, the non-isolated stage 204 may further comprise a logic device 216 for supplying a digital output to a digital-to-analog converter (DAC) 218, which in turn supplies a corresponding analog signal to an input of the power amplifier 212. In certain forms the logic device 216 may comprise a programmable gate array (PGA), a field-programmable gate array (FPGA), programmable logic device (PLD), among other logic circuits, for example. The logic device 216, by virtue of controlling the input of the power amplifier 212 via the DAC 218, may therefore control any of a number of parameters (e.g., frequency, waveform shape, waveform amplitude) of drive signals appearing at the drive signal outputs 210 a, 210 b, 210 c. In certain forms and as discussed below, the logic device 216, in conjunction with a processor (e.g., a digital signal processor discussed below), may implement a number of digital signal processing (DSP)-based and/or other control techniques to control parameters of the drive signals output by the generator 200.

Power may be supplied to a power rail of the power amplifier 212 by a switch-mode regulator 220. In certain forms the switch-mode regulator 220 may comprise an adjustable buck regulator, for example. The non-isolated stage 204 may further comprise a first processor such as DSP processor 222, which in one form may comprise a DSP processor such as an Analog Devices ADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass., for example, although in various forms any suitable processor may be employed. In certain forms the DSP processor 222 may control operation of the switch-mode power converter 220 responsive to voltage feedback data received from the power amplifier 212 by the DSP processor 222 via an analog-to-digital converter (ADC) 224. In one form, for example, the DSP processor 222 may receive as input, via the ADC 224, the waveform envelope of a signal (e.g., an RF signal) being amplified by the power amplifier 212. The DSP processor 222 may then control the switch-mode regulator 220 (e.g., via a pulse-width modulated (PWM) output) such that the rail voltage supplied to the power amplifier 212 tracks the waveform envelope of the amplified signal. By dynamically modulating the rail voltage of the power amplifier 212 based on the waveform envelope, the efficiency of the power amplifier 212 may be significantly improved relative to a fixed rail voltage amplifier schemes.

In certain forms, the logic device 216, in conjunction with the DSP processor 222, may implement a direct digital synthesizer (DDS) control scheme to control the waveform shape, frequency and/or amplitude of drive signals output by the generator 200. In one form, for example, the logic device 216 may implement a DDS control technique by recalling waveform samples stored in a dynamically-updated look-up table (LUT), such as a RAM LUT, which may be embedded in an FPGA. This control technique is particularly useful for ultrasonic applications in which an ultrasonic transducer, such as the ultrasonic transducer 120 (FIGS. 1-3), may be driven by a clean sinusoidal current at its resonant frequency. Because other frequencies may excite parasitic resonances, minimizing or reducing the total distortion of the motional branch current may correspondingly minimize or reduce undesirable resonance effects. Because the waveform shape of a drive signal output by the generator 200 is impacted by various sources of distortion present in the output drive circuit (e.g., the power transformer 206, the power amplifier 212), voltage and current feedback data based on the drive signal may be input into a technique, such as an error control technique implemented by the DSP processor 222, which compensates for distortion by suitably pre-distorting or modifying the waveform samples stored in the LUT on a dynamic, ongoing basis (e.g., in real-time). In one form, the amount or degree of pre-distortion applied to the LUT samples may be based on the error between a computed motional branch current and a desired current waveform shape, with the error being determined on a sample-by-sample basis. In this way, the pre-distorted LUT samples, when processed through the drive circuit, may result in a motional branch drive signal having the desired waveform shape (e.g., sinusoidal) for optimally driving the ultrasonic transducer. In such forms, the LUT waveform samples will therefore not represent the desired waveform shape of the drive signal, but rather the waveform shape that is required to ultimately produce the desired waveform shape of the motional branch drive signal when distortion effects are taken into account.

The non-isolated stage 204 may further comprise an ADC 226 and an ADC 228 coupled to the output of the power transformer 206 via respective isolation transformers 230, 232 for respectively sampling the voltage and current of drive signals output by the generator 200. In certain forms, the ADCs 226, 228 may be configured to sample at high speeds (e.g., 80 MSPS) to enable oversampling of the drive signals. In one form, for example, the sampling speed of the ADCs 226, 228 may enable approximately 200× (depending on frequency) oversampling of the drive signals. In certain forms, the sampling operations of the ADC 226, 228 may be performed by a singe ADC receiving input voltage and current signals via a two-way multiplexer. The use of high-speed sampling in forms of the generator 200 may enable, among other things, calculation of the complex current flowing through the motional branch (which may be used in certain forms to implement DDS-based waveform shape control described herein), accurate digital filtering of the sampled signals, and calculation of real power consumption with a high degree of precision. Voltage and current feedback data output by the ADCs 226, 228 may be received and processed (e.g., FIFO buffering, multiplexing) by the logic device 216 and stored in data memory for subsequent retrieval by, for example, the DSP processor 222. As noted above, voltage and current feedback data may be used as input to a technique for pre-distorting or modifying LUT waveform samples on a dynamic and ongoing basis. In certain forms, this may require each stored voltage and current feedback data pair to be indexed based on, or otherwise associated with, a corresponding LUT sample that was output by the logic device 216 when the voltage and current feedback data pair was acquired. Synchronization of the LUT samples and the voltage and current feedback data in this manner contributes to the correct timing and stability of the pre-distortion technique.

In certain forms, the voltage and current feedback data may be used to control the frequency and/or amplitude (e.g., current amplitude) of the drive signals. In one form, for example, voltage and current feedback data may be used to determine impedance phase. The frequency of the drive signal may then be controlled to minimize or reduce the difference between the determined impedance phase and an impedance phase setpoint (e.g., 0°), thereby minimizing or reducing the effects of ultrasonic distortion and correspondingly enhancing impedance phase measurement accuracy. The determination of phase impedance and a frequency control signal may be implemented in the DSP processor 222, for example, with the frequency control signal being supplied as input to a DDS control technique implemented by the logic device 216.

In another form, for example, the current feedback data may be monitored in order to maintain the current amplitude of the drive signal at a current amplitude setpoint. The current amplitude setpoint may be specified directly or determined indirectly based on specified voltage amplitude and power setpoints. In certain forms, control of the current amplitude may be implemented by control technique, such as, for example, a PID control technique, in the DSP processor 222. Variables controlled by the control technique to suitably control the current amplitude of the drive signal may include, for example, the scaling of the LUT waveform samples stored in the logic device 216 and/or the full-scale output voltage of the DAC 218 (which supplies the input to the power amplifier 212) via a DAC 234.

The non-isolated stage 204 may further comprise a second processor such as UI processor 236 for providing, among other things user interface (UI) functionality. In one form, the UI processor 236 may comprise an Atmel AT91SAM9263 processor having an ARM 926EJ-S core, available from Atmel Corporation, San Jose, Calif., for example. Examples of UI functionality supported by the UI processor 236 may include audible and visual user feedback, communication with peripheral devices (e.g., via a Universal Serial Bus (USB) interface), communication with the foot switch 130, communication with an input device 118 (e.g., a touch screen display) and communication with an output device 112 (e.g., a speaker), as shown in FIG. 3, for example. The UI processor 236 may communicate with the DSP processor 222 and the logic device 216 (e.g., via serial peripheral interface (SPI) buses). Although the UI processor 236 may primarily support UI functionality, it also may coordinate with the DSP processor 222 to implement hazard mitigation in certain forms. For example, the UI processor 236 may be programmed to monitor various aspects of user input and/or other inputs (e.g., touch screen inputs, foot switch 130 inputs (FIG. 3), temperature sensor inputs) and may disable the drive output of the generator 200 when an erroneous condition is detected.

In certain forms, both the DSP processor 222 and the UI processor 236, for example, may determine and monitor the operating state of the generator 200. For the DSP processor 222, the operating state of the generator 200 may dictate, for example, which control and/or diagnostic processes are implemented by the DSP processor 222. For the UI processor 236, the operating state of the generator 200 may dictate, for example, which elements of a user interface (e.g., display screens, sounds) are presented to a user. The respective DSP and UI processors 222, 236 may independently maintain the current operating state of the generator 200 and recognize and evaluate possible transitions out of the current operating state. The DSP processor 222 may function as the master in this relationship and determine when transitions between operating states are to occur. The UI processor 236 may be aware of valid transitions between operating states and may confirm if a particular transition is appropriate. For example, when the DSP processor 222 instructs the UI processor 236 to transition to a specific state, the UI processor 236 may verify that requested transition is valid. In the event that a requested transition between states is determined to be invalid by the UI processor 236, the UI processor 236 may cause the generator 200 to enter a failure mode.

The non-isolated stage 204 may further comprise a controller 238 for monitoring input devices 110 (e.g., a capacitive touch sensor used for turning the generator 200 on and off, a capacitive touch screen, e.g., as shown in FIGS. 1 and 3). In certain forms, the controller 238 may comprise at least one processor and/or other controller device in communication with the UI processor 236. In one form, for example, the controller 238 may comprise a processor (e.g., a Mega168 8-bit controller available from Atmel) configured to monitor user input provided via one or more capacitive touch sensors. In one form, the controller 238 may comprise a touch screen controller (e.g., a QT5480 touch screen controller available from Atmel) to control and manage the acquisition of touch data from a capacitive touch screen.

In certain forms, when the generator 200 is in a “power off” state, the controller 238 may continue to receive operating power (e.g., via a line from a power supply of the generator 200. In this way, the controller 238 may continue to monitor an input device 110 (e.g., a capacitive touch sensor located on a front panel of the generator 200) for turning the generator 200 on and off. When the generator 200 is in the power off state, the controller 238 may wake the power supply (e.g., enable operation of one or more DC/DC voltage converters of the power supply) if activation of the “on/off” input device 110 by a user is detected. The controller 238 may therefore initiate a sequence for transitioning the generator 200 to a “power on” state. Conversely, the controller 238 may initiate a sequence for transitioning the generator 200 to the power off state if activation of the “on/off” input device 110 is detected when the generator 200 is in the power on state. In certain forms, for example, the controller 238 may report activation of the “on/off” input device 110 to the UI processor 236, which in turn implements the necessary process sequence for transitioning the generator 200 to the power off state. In such forms, the controller 238 may have no independent ability for causing the removal of power from the generator 200 after its power on state has been established.

In certain forms, the controller 238 may cause the generator 200 to provide audible or other sensory feedback for alerting the user that a power on or power off sequence has been initiated. Such an alert may be provided at the beginning of a power on or power off sequence and prior to the commencement of other processes associated with the sequence.

In certain forms, the isolated stage 202 may comprise an instrument interface circuit 240 to, for example, provide a communication interface between a control circuit of a surgical device (e.g., a control circuit comprising hand piece switches) and components of the non-isolated stage 204, such as, for example, the programmable logic device 216, the DSP processor 222 and/or the UI processor 236. The instrument interface circuit 240 may exchange information with components of the non-isolated stage 204 via a communication link that maintains a suitable degree of electrical isolation between the stages 202, 204, such as, for example, an infrared (IR)-based communication link. Power may be supplied to the instrument interface circuit 240 using, for example, a low-dropout voltage regulator powered by an isolation transformer driven from the non-isolated stage 204.

In one form, the instrument interface circuit 240 may comprise a logic device 242 (e.g., logic circuit, programmable logic circuit, PGA, FPGA, PLD) in communication with a signal conditioning circuit 242. The signal conditioning circuit 244 may be configured to receive a periodic signal from the logic circuit 242 (e.g., a 2 kHz square wave) to generate a bipolar interrogation signal having an identical frequency. The interrogation signal may be generated, for example, using a bipolar current source fed by a differential amplifier. The interrogation signal may be communicated to a surgical device control circuit (e.g., by using a conductive pair in a cable that connects the generator 200 to the surgical device) and monitored to determine a state or configuration of the control circuit. The control circuit may comprise a number of switches, resistors and/or diodes to modify one or more characteristics (e.g., amplitude, rectification) of the interrogation signal such that a state or configuration of the control circuit is uniquely discernable based on the one or more characteristics. In one form, for example, the signal conditioning circuit 244 may comprises an ADC for generating samples of a voltage signal appearing across inputs of the control circuit resulting from passage of interrogation signal therethrough. The logic device 242 (or a component of the non-isolated stage 204) may then determine the state or configuration of the control circuit based on the ADC samples.

In one form, the instrument interface circuit 240 may comprise a first data circuit interface 246 to enable information exchange between the logic circuit 242 (or other element of the instrument interface circuit 240) and a first data circuit disposed in or otherwise associated with a surgical device. In certain forms, for example, a first data circuit 136 (FIG. 2) may be disposed in a cable integrally attached to a surgical device hand piece, or in an adaptor for interfacing a specific surgical device type or model with the generator 200. The first data circuit 136 may be implemented in any suitable manner and may communicate with the generator according to any suitable protocol including, for example, as described herein with respect to the first circuit 136. In certain forms, the first data circuit may comprise a non-volatile storage device, such as an electrically erasable programmable read-only memory (EEPROM) device. In certain forms and referring again to FIG. 5, the first data circuit interface 246 may be implemented separately from the logic device 242 and comprise suitable circuitry (e.g., discrete logic devices, a processor) to enable communication between the programmable logic device 242 and the first data circuit. In other forms, the first data circuit interface 246 may be integral with the logic device 242.

In certain forms, the first data circuit 136 (FIG. 2) may store information pertaining to the particular surgical device with which it is associated. Such information may include, for example, a model number, a serial number, a number of operations in which the surgical device has been used, and/or any other type of information. This information may be read by the instrument interface circuit 1098 (e.g., by the logic device 242), transferred to a component of the non-isolated stage 204 (e.g., to logic device 216, DSP processor 222 and/or UI processor 236) for presentation to a user via an output device 112 (FIGS. 1 and 3) and/or for controlling a function or operation of the generator 200. Additionally, any type of information may be communicated to first data circuit 136 for storage therein via the first data circuit interface 246 (e.g., using the logic device 242). Such information may comprise, for example, an updated number of operations in which the surgical device has been used and/or dates and/or times of its usage.

As discussed previously, a surgical instrument may be detachable from a hand piece (e.g., as shown in FIGS. 1 and 2, the transducer 120 and the shaft 126 is detachable from the handpiece 105 of the ultrasonic surgical instrument 104) to promote instrument interchangeability and/or disposability. In such cases, conventional generators may be limited in their ability to recognize particular instrument configurations being used and to optimize control and diagnostic processes accordingly. The addition of readable data circuits to surgical device instruments to address this issue is problematic from a compatibility standpoint, however. For example, designing a surgical device to remain backwardly compatible with generators that lack the requisite data reading functionality may be impractical due to, for example, differing signal schemes, design complexity, and cost. Forms of instruments discussed herein address these concerns by using data circuits that may be implemented in existing surgical instruments economically and with minimal design changes to preserve compatibility of the surgical devices with current generator platforms.

Wth reference to FIGS. 1-3 and 5, additionally, forms of the generator 200 may enable communication with instrument-based data circuits. For example, the generator 200 may be configured to communicate with a second data circuit 138 contained in the ultrasonic surgical instrument 104 (e.g., and/or the other surgical instruments 106, 108). In some forms, the second data circuit 138 may be implemented in a many similar to that of the first data circuit 136 described herein. The instrument interface circuit 240 may comprise a second data circuit interface 248 to enable this communication. In one form, the second data circuit interface 248 may comprise a tri-state digital interface, although other interfaces also may be used. In certain forms, the second data circuit may generally be any circuit for transmitting and/or receiving data. In one form, for example, the second data circuit may store information pertaining to the particular surgical instrument with which it is associated. Such information may include, for example, a model number, a serial number, a number of operations in which the surgical instrument has been used, and/or any other type of information. In some forms, the second data circuit 138 may store information about the electrical and/or ultrasonic properties of an associated transducer 120, end effector 122, or ultrasonic drive system. For example, the first data circuit 136 may indicate a burn-in frequency slope, as described herein. Additionally or alternatively, any type of information may be communicated to second data circuit for storage therein via the second data circuit interface 248 (e.g., using the logic device 242). Such information may comprise, for example, an updated number of operations in which the instrument has been used and/or dates and/or times of its usage. In certain forms, the second data circuit may transmit data acquired by one or more sensors (e.g., an instrument-based temperature sensor). In certain forms, the second data circuit may receive data from the generator 200 and provide an indication to a user (e.g., an LED indication or other visible indication) based on the received data.

In certain forms, the second data circuit and the second data circuit interface 248 may be configured such that communication between the logic device 242 and the second data circuit can be effected without the need to provide additional conductors for this purpose (e.g., dedicated conductors of a cable connecting a hand piece to the generator 200). In one form, for example, information may be communicated to and from the second data circuit using a 1-wire bus communication scheme implemented on existing cabling, such as one of the conductors used transmit interrogation signals from the signal conditioning circuit 244 to a control circuit in a hand piece. In this way, design changes or modifications to the surgical device that might otherwise be necessary are minimized or reduced. Moreover, because different types of communications implemented over a common physical channel can be frequency-band separated, the presence of a second data circuit may be “invisible” to generators that do not have the requisite data reading functionality, thus enabling backward compatibility of the surgical device instrument.

In certain forms, the isolated stage 202 may comprise at least one blocking capacitor 250-1 connected to the drive signal output 210 b to prevent passage of DC current to a patient. A single blocking capacitor may be required to comply with medical regulations or standards, for example. While failure in single-capacitor designs is relatively uncommon, such failure may nonetheless have negative consequences. In one form, a second blocking capacitor 250-2 may be provided in series with the blocking capacitor 250-1, with current leakage from a point between the blocking capacitors 250-1, 250-2 being monitored by, for example, an ADC 252 for sampling a voltage induced by leakage current. The samples may be received by the logic device 242, for example. Based changes in the leakage current (as indicated by the voltage samples in the form of FIG. 5), the generator 200 may determine when at least one of the blocking capacitors 250-1, 250-2 has failed. Accordingly, the form of FIG. 5 provides a benefit over single-capacitor designs having a single point of failure.

In certain forms, the non-isolated stage 204 may comprise a power supply 254 for outputting DC power at a suitable voltage and current. The power supply may comprise, for example, a 400 W power supply for outputting a 48 VDC system voltage. The power supply 254 may further comprise one or more DC/DC voltage converters 256 for receiving the output of the power supply to generate DC outputs at the voltages and currents required by the various components of the generator 200. As discussed above in connection with the controller 238, one or more of the DC/DC voltage converters 256 may receive an input from the controller 238 when activation of the “on/off” input device 110 (FIG. 3) by a user is detected by the controller 238 to enable operation of, or wake, the DC/DC voltage converters 256.

Wth reference back to FIG. 1, having described operational details of various forms of the surgical system 100 operations for the above surgical system 100 may be further described generally in terms of a process for cutting and coagulating tissue employing a surgical instrument comprising an input device 110 and the generator 102. Although a particular process is described in connection with the operational details, it can be appreciated that the process merely provides an example of how the general functionality described herein can be implemented by the surgical system 100. Further, the given process does not necessarily have to be executed in the order presented herein unless otherwise indicated. As previously discussed, the input devices 110 may be employed to program the output (e.g., impedance, current, voltage, frequency) of the surgical instruments 104, 106, 108.

FIG. 6 illustrates a generator 300 comprising one form of drive system 302, according to one aspect of the present disclosure. The generator 300 is similar to the generators 102, 200 described in connection with in FIGS. 1 and 5. The generator 300 produces an ultrasonic electrical signal for driving an ultrasonic transducer, also referred to as a drive signal. The drive system 302 is flexible and can create an ultrasonic electrical output drive signal 304 at a desired frequency and power level setting for driving an ultrasonic transducer 306. In various forms, the generator 300 may comprise several separate functional elements, such as modules and/or blocks. Although certain modules, circuits, and/or blocks may be described by way of example, it can be appreciated that a greater or lesser number of modules, circuits, and/or blocks may be used and still fall within the scope of the forms. Further, although various forms may be described in terms of modules, circuits, and/or blocks to facilitate description, such modules, circuits, and/or blocks may be implemented by one or more hardware components, e.g., processors, Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs), Application Specific Integrated Circuits (ASICs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components.

In one form, the drive system 302 of the generator 300 may comprise one or more embedded applications implemented as firmware, software, hardware, or any combination thereof. The drive system 302 may comprise various executable modules such as software, programs, data, drivers, application program interfaces (APIs), and so forth. The firmware may be stored in nonvolatile memory (NVM), such as in bit-masked read-only memory (ROM) or flash memory. In various implementations, storing the firmware in ROM may preserve flash memory. The NVM may comprise other types of memory including, for example, programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or battery backed random-access memory (RAM) such as dynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronous DRAM (SDRAM).

In one form, the drive system 302 comprises a hardware component implemented as a processor 308 for executing program instructions for monitoring various measurable characteristics of the ultrasonic surgical instrument 104 (FIG. 1) and generating various functions as an output signal for driving the ultrasonic transducer 306 in cutting and/or coagulation operating modes. It will be appreciated by those skilled in the art that the generator 300 and the drive system 302 may comprise additional or fewer components and only a simplified version of the generator 300 and the drive system 302 are described herein for conciseness and clarity. In various forms, as previously discussed, the hardware component may be implemented as a DSP, PLD, ASIC, circuits, and/or registers. In one form, the processor 308 may be configured to store and execute computer software program instructions to generate the output signal functions for driving various components of the ultrasonic surgical instrument 104 (FIG. 1), such as an ultrasonic transducer 306, an end effector, and/or a blade 340.

In one form, under control of one or more software program routines, the processor 308 executes the methods in accordance with the described forms to generate a function formed by a stepwise waveform of drive signals comprising current (I), voltage (V), and/or frequency (f) for various time intervals or periods (T). The stepwise waveforms of the drive signals may be generated by forming a piecewise linear combination of constant functions over a plurality of time intervals created by varying the generator 300 drive signals, e.g., output drive current (I), voltage (V), and/or frequency (f). The time intervals or periods (T) may be predetermined (e.g., fixed and/or programmed by the user) or may be variable. Variable time intervals may be defined by setting the drive signal to a first value and maintaining the drive signal at that value until a change is detected in a monitored characteristic. Examples of monitored characteristics may comprise, for example, transducer impedance, tissue impedance, tissue heating, tissue transection, tissue coagulation, and the like. The ultrasonic drive signals generated by the generator 300 include, without limitation, ultrasonic drive signals capable of exciting the ultrasonic transducer 306 in various vibratory modes such as, for example, the primary longitudinal mode and harmonics thereof as well flexural and torsional vibratory modes.

In one form, the executable modules comprise one or more technique(s) 310 stored in memory that when executed causes the processor 308 to generate a function formed by a stepwise waveform of drive signals comprising current (I), voltage (V), and/or frequency (f) for various time intervals or periods (T). The stepwise waveforms of the drive signals may be generated by forming a piecewise linear combination of constant functions over two or more time intervals created by varying the generator 300 output drive current (I), voltage (V), and/or frequency (f). The drive signals may be generated either for predetermined fixed time intervals or periods (T) of time or variable time intervals or periods of time in accordance with the one or more technique(s) 310. Under control of the processor 308, the generator 300 varies (e.g., increment or decrement over time) the current (I), voltage (V), and/or frequency (f) up or down at a particular resolution for a predetermined period (T) or until a predetermined condition is detected, such as a change in a monitored characteristic (e.g., transducer impedance, tissue impedance). The steps can change in programmed increments or decrements. If other steps are desired, the generator 300 can increase or decrease the step adaptively based on measured system characteristics.

In operation, the user can program the operation of the generator 300 using the input device 312 located on the front panel of the generator 300 console. The input device 312 may comprise any suitable device that generates signals 314 that can be applied to the processor 308 to control the operation of the generator 300. In various forms, the input device 312 includes buttons, switches, thumbwheels, keyboard, keypad, touch screen monitor, pointing device, remote connection to a general purpose or dedicated computer. In other forms, the input device 312 may comprise a suitable user interface. Accordingly, by way of the input device 312, the user can set or program the current (I), voltage (V), frequency (f), and/or period (T) for programming the output function of the generator 300. The processor 308 then displays the selected power level by sending a signal on line 316 to an output indicator 318.

In various forms, the output indicator 318 may provide visual, audible, and/or tactile feedback to the surgeon to indicate the status of a surgical procedure, such as, for example, when tissue cutting and coagulating is complete based on a measured characteristic of the ultrasonic surgical instrument 104 (FIG. 1), e.g., transducer impedance, tissue impedance, or other measurements as subsequently described. By way of example, and not limitation, visual feedback comprises any type of visual indication device including incandescent lamps or light emitting diodes (LEDs), graphical user interface, display, analog indicator, digital indicator, bar graph display, digital alphanumeric display. By way of example, and not limitation, audible feedback comprises any type of buzzer, computer generated tone, computerized speech, voice user interface (VUI) to interact with computers through a voice/speech platform. By way of example, and not limitation, tactile feedback comprises any type of vibratory feedback provided through an instrument housing handle assembly.

In one form, the processor 308 may be configured or programmed to generate a digital current drive signal 320 and a digital frequency signal 322. These drive signals 320, 322 are applied to a direct digital synthesizer (DDS) circuit 324 to adjust the amplitude and the frequency (f) of the output drive signal 304 to the ultrasonic transducer 306. The output of the DDS circuit 324 is applied to an amplifier 326 whose output is applied to a transformer 328. The output of the transformer 328 is the output drive signal 304 applied to the ultrasonic transducer 306, which is coupled to the blade 340 by way of a waveguide.

In one form, the generator 300 comprises one or more measurement modules or components that may be configured to monitor measurable characteristics of the ultrasonic surgical instrument 104 (FIG. 1). In the illustrated form, the processor 308 may be employed to monitor and calculate system characteristics. As shown, the processor 308 measures the impedance Z of the ultrasonic transducer 306 by monitoring the current supplied to the transducer 306 and the voltage applied to the ultrasonic transducer 306. In one form, a current sense circuit 330 is employed to sense the current supplied to the ultrasonic transducer 306 and a voltage sense circuit 332 is employed to sense the output voltage applied to the ultrasonic transducer 306. These signals may be applied to the analog-to-digital converter 336 (ADC) via an analog multiplexer 334 circuit or switching circuit arrangement. The analog multiplexer 334 routes the appropriate analog signal to the ADC 336 for conversion. In other forms, multiple ADCs 336 may be employed for each measured characteristic instead of the multiplexer 334 circuit. The processor 308 receives the digital output 338 of the ADC 336 and calculates the transducer impedance Z based on the measured values of current and voltage. The processor 308 adjusts the output drive signal 304 such that it can generate a desired power versus load curve. In accordance with programmed techniques 310, the processor 308 can vary the drive signal 320, e.g., the current or frequency, in any suitable increment or decrement in response to the transducer impedance Z.

Having described operational details of various forms of the surgical system 100 shown in FIG. 1, operations for the above surgical system 100 may be further described in terms of a process for cutting and coagulating a blood vessel employing a surgical instrument comprising the input device 110 and the transducer impedance measurement capabilities of the drive system 302 described with reference to FIG. 6. Although a particular process is described in connection with the operational details, it can be appreciated that the process merely provides an example of how the general functionality described herein can be implemented by the surgical system 100. Further, the given process does not necessarily have to be executed in the order presented herein unless otherwise indicated.

FIG. 7 illustrates one aspect of a drive system of a generator 400 comprising a tissue impedance module 442. The drive system 402 generates the ultrasonic electrical drive signal 404 to drive the ultrasonic transducer 406. In one aspect, the tissue impedance module 442 may be configured to measure the impedance Zt of tissue grasped between the blade 440 and the clamp arm assembly 444. The tissue impedance module 442 comprises an RF oscillator 446, a voltage sensing circuit 448, and a current sensing circuit 450. The voltage and current sensing circuits 448, 450 respond to the RF voltage Vrf applied to the blade 440 electrode and the RF current irf flowing through the blade 440 electrode, the tissue, and the conductive portion of the clamp arm assembly 444. The sensed current Irf and the sensed voltage Vrf from the current sense circuit 430 and the voltage sense circuit 432 are converted to digital form by the ADC 436 via the analog multiplexer 434. The processor 408 receives the digitized output 438 of the ADC 436 and determines the tissue impedance Zt by calculating the ratio of the RF voltage Vrf to current Irf measured by the voltage sensing circuit 448 and the current sense circuit 450.

In one form, the processor 408 may be configured or programmed to generate a digital current signal 420 and a digital frequency signal 422. These signals 420, 422 are applied to a direct digital synthesizer (DDS) circuit 424 to adjust the amplitude and the frequency (f) of the current output signal 404 to the transducer 406. The output of the DDS circuit 424 is applied to an amplifier 426 whose output is applied to a transformer 428. The output of the transformer 428 is the signal 404 applied to the ultrasonic transducer 406, which is coupled to the blade 440 by way of a waveguide.

In one aspect, the transection of the inner muscle layer and the tissue may be detected by sensing the tissue impedance Zt. Accordingly, detection of the tissue impedance Zt may be integrated with an automated process for separating the inner muscle layer from the outer adventitia layer prior to transecting the tissue without causing a significant amount of heating, which normally occurs at resonance.

In one form, the RF voltage Vrf applied to the blade 440 electrode and the RF current Irf flowing through the blade 440 electrode, the tissue, and the conductive portion of the clamp arm assembly 444 are suitable for vessel sealing and//or dissecting. Thus, the RF power output of the generator 400 can be selected for non-therapeutic functions such as tissue impedance measurements as well as therapeutic functions such as vessel sealing and/or dissection. It will be appreciated, that in the context of the present disclosure, the ultrasonic and the RF electrosurgical energies can be supplied by the generator either individually or simultaneously.

In operation, the user can program the operation of the generator 400 using the input device 412 located on the front panel of the generator 400 console. The input device 412 may comprise any suitable device that generates signals 414 that can be applied to the processor 408 to control the operation of the generator 400. In various forms, the input device 412 includes buttons, switches, thumbwheels, keyboard, keypad, touch screen monitor, pointing device, remote connection to a general purpose or dedicated computer. In other forms, the input device 412 may comprise a suitable user interface. Accordingly, by way of the input device 412, the user can set or program the current (I), voltage (V), frequency (f), and/or period (T) for programming the function output of the generator 400. The processor 408 then displays the selected power level by sending a signal on line 416 to an output indicator 418.

In various forms, feedback is provided by the output indicator 418. The output indicator 418 is particularly useful in applications where the tissue being manipulated by the end effector is out of the user's field of view and the user cannot see when a change of state occurs in the tissue. The output indicator 418 communicates to the user that a change in tissue state has occurred. As previously discussed, the output indicator 418 may be configured to provide various types of feedback to the user including, without limitation, visual, audible, and/or tactile feedback to indicate to the user (e.g., surgeon, clinician) that the tissue has undergone a change of state or condition of the tissue. By way of example, and not limitation, as previously discussed, visual feedback comprises any type of visual indication device including incandescent lamps or LEDs, graphical user interface, display, analog indicator, digital indicator, bar graph display, digital alphanumeric display. By way of example, and not limitation, audible feedback comprises any type of buzzer, computer generated tone, computerized speech, VUI to interact with computers through a voice/speech platform. By way of example, and not limitation, tactile feedback comprises any type of vibratory feedback provided through the instrument housing handle assembly. The change of state of the tissue may be determined based on transducer and tissue impedance measurements as previously described, or based on voltage, current, and frequency measurements.

In one form, the various executable modules (e.g., algorithms 410) comprising computer readable instructions can be executed by the processor 408 portion of the generator 400. In various forms, the operations described with respect to the techniques may be implemented as one or more software components, e.g., programs, subroutines, logic; one or more hardware components, e.g., processors, DSPs, PLDs, ASICs, circuits, registers; and/or combinations of software and hardware. In one form, the executable instructions to perform the techniques may be stored in memory. When executed, the instructions cause the processor 408 to determine a change in tissue state provide feedback to the user by way of the output indicator 418. In accordance with such executable instructions, the processor 408 monitors and evaluates the voltage, current, and/or frequency signal samples available from the generator 400 and according to the evaluation of such signal samples determines whether a change in tissue state has occurred. As further described below, a change in tissue state may be determined based on the type of ultrasonic instrument and the power level that the instrument is energized at. In response to the feedback, the operational mode of the ultrasonic surgical instrument may be controlled by the user or may be automatically or semi-automatically controlled.

As noted above, a single output generator can deliver both RF and ultrasonic energy through a single port and these signals can be delivered separately or simultaneously to the end effector to treat tissue. A single output port generator can include a single output transformer with multiple taps to provide power, either RF or ultrasonic energy, to the end effector depending on the type of treatment of tissue being performed. For example, the generator can deliver energy with higher voltage and lower current to drive an ultrasonic transducer, with lower voltage and higher current as required to drive electrodes for sealing tissue, or with a coagulation waveform for spot coagulation using either monopolar or bipolar electrosurgical electrodes. The output waveform from the generator can be steered, switched, or filtered to provide the desired frequency to the end effector of the surgical instrument.

FIG. 8 illustrates an example of a generator 500 for delivering multiple energy modalities to a surgical instrument. The generator 500 is similar to the generator 102 described in connection with FIG. 1 and includes functionalities of the generators 200, 300, 400 shown in FIGS. 5-7. For conciseness and clarity of disclosure, hereinbelow, the various logic flow diagrams are described in connection with the generator 500, which is a high level block diagram representation. Accordingly, the reader is directed to the description of the functional blocks of the generators 200, 300, 400 in FIGS. 5-7 for additional details that may be necessary to understand and practice the logic flow diagrams described hereinbelow in connection with the generator 500.

Turning back to FIG. 8, the generator 500 provides radio frequency and ultrasonic signals for delivering energy to a surgical instrument. The radio frequency and ultrasonic signals may be provided alone or in combination and may be provided simultaneously. As noted above, at least one generator output can deliver multiple energy modalities (e.g., ultrasonic, bipolar or monopolar RF, irreversible and/or reversible electroporation, and/or microwave energy, among others) through a single port and these signals can be delivered separately or simultaneously to the end effector to treat tissue. The generator 500 comprises a processor 502 coupled to a waveform generator 504. The processor 502 and waveform generator 504 are configured to generate a variety of signal waveforms based on information stored in a memory coupled to the processor 502, not shown for clarity of disclosure. The digital information associated with a waveform is provided to the waveform generator 504 which includes one or more digital-to-analog (DAC) converters to convert the digital input into an analog output. The analog output is fed to an amplifier 1106 for signal conditioning and amplification. The conditioned and amplified output of the amplifier 506 is coupled to a power transformer 508. The signals are coupled across the power transformer 508 to the secondary side, which is in the patient isolation side. A first signal of a first energy modality is provided to the surgical instrument between the terminals labeled ENERGY1 and RETURN. A second signal of a second energy modality is coupled across a capacitor 510 and is provided to the surgical instrument between the terminals labeled ENERGY2 and RETURN. It will be appreciated that more than two energy modalities may be output and thus the subscript “n” may be used to designate that up to n ENERGYn terminals may be provided, where n is a positive integer greater than 1. It also will be appreciated that up to “n” return paths RETURNn may be provided without departing from the scope of the present disclosure.

A first voltage sensing circuit 512 is coupled across the terminals labeled ENERGY1 and the RETURN path to measure the output voltage therebetween. A second voltage sensing circuit 524 is coupled across the terminals labeled ENERGY2 and the RETURN path to measure the output voltage therebetween. A current sensing circuit 514 is disposed in series with the RETURN leg of the secondary side of the power transformer 508 as shown to measure the output current for either energy modality. If different return paths are provided for each energy modality, then a separate current sensing circuit should be provided in each return leg. The outputs of the first and second voltage sensing circuits 512, 524 are provided to respective isolation transformers 516, 522 and the output of the current sensing circuit 514 is provided to another isolation transformer 518. The outputs of the isolation transformers 516, 518, 522 in the on the primary side of the power transformer 508 (non-patient-isolated side) are provided to a one or more analog-to-digital converters 526 (ADC). The digitized output of the ADC 526 is provided to the processor 502 for further processing and computation. The output voltages and output current feedback information can be employed to adjust the output voltage and current provided to the surgical instrument and to compute output impedance, among other parameters. Input/output communications between the processor 502 and patient isolated circuits is provided through an interface circuit 520. Sensors also may be in electrical communication with the processor 502 by way of the interface 520.

In one aspect, the impedance may be determined by the processor 502 by dividing the output of either the first voltage sensing circuit 512 coupled across the terminals labeled ENERGY1/RETURN or the second voltage sensing circuit 524 coupled across the terminals labeled ENERGY2/RETURN by the output of the current sensing circuit 514 disposed in series with the RETURN leg of the secondary side of the power transformer 508. The outputs of the first and second voltage sensing circuits 512, 524 are provided to separate isolations transformers 516, 522 and the output of the current sensing circuit 514 is provided to another isolation transformer 516. The digitized voltage and current sensing measurements from the ADC 526 are provided the processor 502 for computing impedance. As an example, the first energy modality ENERGY1 may be ultrasonic energy and the second energy modality ENERGY2 may be RF energy. Nevertheless, in addition to ultrasonic and bipolar or monopolar RF energy modalities, other energy modalities include irreversible and/or reversible electroporation and/or microwave energy, among others. Also, although the example illustrated in FIG. 8 shows a single return path RETURN may be provided for two or more energy modalities, in other aspects multiple return paths RETURNn may be provided for each energy modality ENERGYn. Thus, as described herein, the ultrasonic transducer impedance may be measured by dividing the output of the first voltage sensing circuit 512 by the current sensing circuit 514 and the tissue impedance may be measured by dividing the output of the second voltage sensing circuit 524 by the current sensing circuit 514.

As shown in FIG. 8, the generator 500 comprising at least one output port can include a power transformer 508 with a single output and with multiple taps to provide power in the form of one or more energy modalities, such as ultrasonic, bipolar or monopolar RF, irreversible and/or reversible electroporation, and/or microwave energy, among others, for example, to the end effector depending on the type of treatment of tissue being performed. For example, the generator 500 can deliver energy with higher voltage and lower current to drive an ultrasonic transducer, with lower voltage and higher current to drive RF electrodes for sealing tissue, or with a coagulation waveform for spot coagulation using either monopolar or bipolar RF electrosurgical electrodes. The output waveform from the generator 500 can be steered, switched, or filtered to provide the frequency to the end effector of the surgical instrument. The connection of an ultrasonic transducer to the generator 500 output would be preferably located between the output labeled ENERGY1 and RETURN as shown in FIG. 8. An In one example, a connection of RF bipolar electrodes to the generator 500 output would be preferably located between the output labeled ENERGY2 and RETURN. In the case of monopolar output, the preferred connections would be active electrode (e.g., pencil or other probe) to the ENERGY2 output and a suitable return pad connected to the RETURN output.

In other aspects, the generators 102, 200, 300, 400, 500 described in connection with FIGS. 1-3 and 5-8, the ultrasonic generator drive circuit 114, and/or electrosurgery/RF drive circuit 116 as described in connection with FIG. 3 may be formed integrally with any one of the surgical instruments 104, 106, 108 described in connection with FIGS. 1 and 2. Accordingly, any of the processors, digital signal processors, circuits, controllers, logic devices, ADCs, DACs, amplifiers, converters, transformers, signal conditioners, data interface circuits, current and voltage sensing circuits, direct digital synthesis circuits, multiplexer (analog or digital), waveform generators, RF generators, memory, and the like, described in connection with any one of the generators 102, 200, 300, 400, 500 can be located within the surgical instruments 104, 106, 108 or may be located remotely from the surgical instruments 104, 106, 108 and coupled to the surgical instruments via wired and/or wireless electrical connections.

Examples of waveforms representing energy for delivery from a generator are illustrated in FIGS. 9-13. FIG. 9 illustrates an example graph 600 showing first and second individual waveforms representing an RF output signal 602 and an ultrasonic output signal 604 superimposed on the same time and voltage scale for comparison purposes. These output signals 602, 604 are provided at the ENERGY output of the generator 500 shown in FIG. 8. Time (t) is shown along the horizontal axis and voltage (V) is shown along the vertical axis. The RF output signal 602 has a frequency of about 330 kHz RF and a peak-to-peak voltage of ±1V. The ultrasonic output signal 604 has a frequency of about 55 kHz and a peak-to-peak voltage of ±1V. It will be appreciated that the time (t) scale along the horizontal axis and the voltage (V) scale along the vertical axis are normalized for comparison purposes and may be different actual implementations, or represent other electrical parameters such as current.

FIG. 10 illustrates an example graph 610 showing the sum of the two output signals 602, 604 shown in FIG. 9. Time (t) is shown along the horizontal axis and voltage (V) is shown along the vertical axis. The sum of the RF output signal 602 and the ultrasonic output signal 604 shown in FIG. 9 produces a combined output signal 612 having a 2V peak-to-peak voltage, which is twice the amplitude of the original RF and ultrasonic signals shown (1V peak-to-peak) shown in FIG. 9. An amplitude of twice the original amplitude can cause problems with the output section of the generator, such as distortion, saturation, clipping of the output, or stresses on the output components. Thus, the management of a single combined output signal 612 that has multiple treatment components is an important aspect of the generator 500 shown in FIG. 8. There are a variety of ways to achieve this management. In one form, one of the two RF or ultrasonic output signals 602, 604 can be dependent on the peaks of the other output signal.

For example, FIG. 11 illustrates an example graph 620 showing a combined output signal 622 representative of a dependent sum of the output signals 602, 604 shown in FIG. 9. Time (t) is shown along the horizontal axis and voltage (V) is shown along the vertical axis. As shown in FIG. 11, the RF output signal 602 component of FIG. 9 depends on the peaks of the ultrasonic output signal 604 component of FIG. 9 such that the amplitude of the RF output signal component of the dependent sum combined output signal 622 is reduced when an ultrasonic peak is anticipated. As shown in the example graph 620 in FIG. 11, the peaks have been reduced from 2 to 1.5. In another form, one of the output signals is a function of the other output signal.

For example, FIG. 11 illustrates an example graph 630 showing an output signal 632 representative of a dependent sum of the output signals 602, 604 shown in FIG. 9. Time (t) is shown along the horizontal axis and voltage (V) is shown along the vertical axis. As shown in FIG. 12, the RF output signal is a function of the ultrasonic output signal. This provides a hard limit on the amplitude of the output. As shown in FIG. 12, the ultrasonic output signal is extractable as a sine wave while the RF output signal has distortion but not in a way to affect the coagulation performance of the RF output signal.

A variety of other techniques can be used for compressing and/or limiting the waveforms of the output signals. It should be noted that the integrity of the ultrasonic output signal 604 (FIG. 9) can be more important than the integrity of the RF output signal 602 (FIG. 9) as long as the RF output signal 602 has low frequency components for safe patient levels so as to avoid neuro-muscular stimulation. In another form, the frequency of an RF waveform can be changed on a continuous basis in order to manage the peaks of the waveform. Waveform control is important as more complex RF waveforms, such as a coagulation-type waveform 644, as illustrated in the graph 640 shown in FIG. 13, are implemented with the system. Again, time (t) is shown along the horizontal axis and voltage (V) is shown along the vertical axis.

FIGS. 14-42 (26-54) illustrate various configurations of sensors, circuits, and techniques for measuring tissue parameters to facilitate executing the various adaptive tissue identification and treatment technique described herein. FIG. 14 illustrates one aspect of an end effector 700 comprising RF data sensors 706, 708 a, 708 b located on the clamp arm 702. The end effector 700 comprises a clamp arm 702 and an ultrasonic blade 704. The clamp arm 702 is shown clamping tissue 710 located between the clamp arm 702 and the ultrasonic blade 704. A first sensor 706 is located in a center portion of the clamp arm 702. Second and third sensors 708 a, 708 b are located on lateral portions of the clamp arm 702. The sensors 706, 708 a, 708 b are mounted or formed integrally with on a flexible circuit 712 (shown more particularly in FIG. 15 and more particularly segmented flexible circuits 800, 900 shown in FIGS. 17 and 18) configured to be fixedly mounted to the clamp arm 702.

The end effector 700 is an example end effector for the multifunction surgical instrument 108 shown in FIGS. 1 and 2. The sensors 706, 708 a, 708 b are electrically connected to an energy source, such as for example, the generator 500 shown in FIG. 8. The sensors 706, 708 a, 708 b are powered by suitable sources within the generator and the signals generated by the sensors 706, 708 a, 708 b are provided to analog and/or digital processing circuits of the generator 500.

In one aspect, the first sensor 706 is a force sensor to measure a normal force F₃ applied to the tissue 710 by the clamp arm 702. The second and third sensors 708 a, 708 b include one or more elements to apply RF energy to the tissue 710, measure tissue impedance, down force F₁, transverse forces F₂, and temperature, among other parameters. Electrodes 709 a, 709 b are electrically coupled to the generator and apply RF energy to the tissue 710. In one aspect, the first sensor 706 and the second and third sensors 708 a, 708 b are strain gauges to measure force or force per unit area. It will be appreciated that the measurements of the down force F₁, the lateral forces F₂, and the normal force F₃ may be readily converted to pressure by determining the surface area upon which the force sensors 706, 708 a, 708 b are acting upon. Additionally, as described with particularity herein, the flexible circuit 712 may comprise temperature sensors embedded in one or more layers of the flexible circuit 712. The one or more temperature sensors may be arranged symmetrically or asymmetrically and provide tissue 710 temperature feedback to control circuits of the generator.

FIG. 15 illustrates one aspect of the flexible circuit 712 shown in FIG. 14 in which the sensors 706, 708 a, 708 b may be mounted to or formed integrally therewith. The flexible circuit 712 is configured to fixedly attach to the clamp arm 702. As shown particularly in FIG. 15, asymmetric temperature sensors 714 a, 714 b are mounted to the flexible circuit 712 to enable measuring the temperature of the tissue 710 (FIG. 14).

FIG. 16 is a cross-sectional view of the flexible circuit 712 shown in FIG. 15. The flexible circuit 712 comprises multiple layers and is fixedly attached to the clamp arm 702. A top layer of the flexible circuit 712 is an electrode 709 a, which is electrically coupled to an energy source, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), to apply RF energy to the tissue 710 (FIG. 14). A layer of electrical insulation 718 is provided below the electrode 709 a layer to electrically isolate the sensors 714 a, 706, 708 a from the electrode 709 a. The temperature sensors 714 a are disposed below the layer of electrical insulation 718. The first force (pressure) sensor 706 is located below the layer containing the temperature sensors 714 a and above a compressive layer 720. The second force (pressure) sensor 708 a is located below the compressive layer 720 and above the clamp arm 702 frame.

FIG. 17 illustrates one aspect of a segmented flexible circuit 800 configured to fixedly attach to a clamp arm 804 of an end effector. The segmented flexible circuit 800 comprises a distal segment 802 a and lateral segments 802 b, 802 c that include individually addressable sensors to provide local tissue control, as described herein in connection with FIGS. 14-16, for example. The segments 802 a, 802 b, 802 c are individually addressable to treat tissue and to measure tissue parameters based on individual sensors located within each of the segments 802 a, 802 b, 802 c. The segments 802 a, 802 b, 802 c of the segmented flexible circuit 800 are mounted to the clamp arm 804 and are electrically coupled to an energy source, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), via electrical conductive elements 806. A Hall effect sensor 808, or any suitable magnetic sensor, is located on a distal end of the clamp arm 804. The Hall effect sensor 808 operates in conjunction with a magnet to provide a measurement of an aperture defined by the clamp arm 804, which otherwise may be referred to as a tissue gap, as shown with particularity in FIG. 19.

FIG. 18 illustrates one aspect of a segmented flexible circuit 900 configured to mount to a clamp arm 904 of an end effector. The segmented flexible circuit 1900 comprises a distal segment 902 a and lateral segments 902 b, 902 c that include individually addressable sensors for tissue control, as described herein in connection with FIGS. 14-17, for example. The segments 902 a, 902 b, 902 c are individually addressable to treat tissue and to read individual sensors located within each of the segments 902 a, 902 b, 902 c. The segments 902 a, 902 b, 902 c of the segmented flexible circuit 900 are mounted to the clamp arm 904 and are electrically coupled to an energy source, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), via electrical conductive elements 906. A Hall effect sensor 908, or other suitable magnetic sensor, is provided on a distal end of the clamp arm 904. The Hall effect sensor 908 operates in conjunction with a magnet to provide a measurement of an aperture defined by the clamp arm 904 of the end effector or tissue gap as shown with particularity in FIG. 19. In addition, a plurality of lateral asymmetric temperature sensors 910 a, 910 b are mounted on or formally integrally with the segmented flexible circuit 900 to provide tissue temperature feedback to control circuits in the generator.

FIG. 19 illustrates one aspect of an end effector 1000 configured to measure a tissue gap G_(T). The end effector 1000 comprises a jaw member 1002 and a clamp arm 904. The flexible circuit 900 as described in FIG. 18, is mounted to the clamp arm 904. The flexible circuit 900 comprises a Hall effect sensor 908 that operates with a magnet 1004 mounted to the jaw member 1002 to measure the tissue gap G_(T). This technique can be employed to measure the aperture defined between the clamp arm 904 and the jaw member 1002. The jaw member 1002 may be an ultrasonic blade.

FIG. 20 illustrates one aspect of a left-right segmented flexible circuit 1100. The left-right segmented flexible circuit 1100 comprises a plurality of segments L1-L5 on the left side of the left-right segmented flexible circuit 1100 and a plurality of segments R1-R5 on the right side of the left-right segmented flexible circuit 1100. Each of the segments L1-L5 and R1-R5 comprise temperature sensors and force sensors to sense tissue parameters locally within each segment L1-L5 and R1-R5. The left-right segmented flexible circuit 1100 are configured to influence the RF treatment energy based on tissue parameters sensed locally within each of the segments L1-L5 and R1-R5.

FIG. 21 illustrates one aspect of an end effector 1200 comprising segmented flexible circuit 1100 as shown in FIG. 20. The end effector 1200 comprises a clamp arm 1202 and an ultrasonic blade 1204. The segmented flexible circuit 1100 is mounted to the clamp arm 1202. Each of the sensors disposed within the segments 1-5 are configured to detect the presence of tissue positioned between the clamp arm 1202 and the ultrasonic blade 1204 and represent tissue zones 1-5. In the configuration shown in FIG. 21, the end effector 1200 is shown in an open position ready to receive or grasp tissue between the clamp arm 1202 and the ultrasonic blade 1204.

FIG. 22 illustrates the end effector 1200 shown in FIG. 21 with the clamp arm 1202 clamping tissue 1206 between the clamp arm 1202 and the ultrasonic blade 1204. As shown in FIG. 22, the tissue 1206 is positioned between segments 1-3 and represents tissue zones 1-3. Accordingly, tissue 1206 is detected by the sensors in segments 1-3 and the absence of tissue (empty) is detected in section 1208 by segments 4-5. The information regarding the presence and absence of tissue 1206 positioned within certain segments 1-3 and 4-5, respectively, is communicated to a control circuit of the generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8). The generator 500 is configured to energize only the segments 1-3 where tissue 1206 is detected and does not energize the segments 4-5 where tissue is not detected. It will be appreciated that the segments 1-5 may contain any suitable temperature, force/pressure, and/or Hall effect magnetic sensors to measure tissue parameters of tissue located within certain segments 1-5 and electrodes to deliver RF energy to tissue located in certain segments 1-5.

FIG. 23 illustrates graphs 1300 of energy applied by the right and left side of an end effector based on locally sensed tissue parameters. As discussed herein, the clamp arm of an end effector may comprise temperature sensors, force/pressure sensors, Hall effector sensors, among others, along the right and left sides of the clamp arm as shown, for example, in FIGS. 14-22. Thus, RF energy can be selectively applied to tissue positioned between the clam jaw and the ultrasonic blade. The top graph 1302 depicts power P_(R) applied to a right side segment of the clamp arm versus time (t) based on locally sensed tissue parameters. Thus, the generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), is configured to measure the sensed tissue parameters and to apply power P_(R) to a right side segment of the clamp arm. The generator 500 delivers an initial power level P₁ to the tissue via the right side segment and then decreases the power level to P₂ based on local sensing of tissue parameters (e.g., temperature, force/pressure, thickness) in one or more segments. The bottom graph 1304 depicts power P_(L) applied to a left side segment of the clamp arm versus time (t) based on locally sensed tissue parameters. The generator 500 delivers an initial power level of P₁ to the tissue via the left side segment and then increases the power level to P₃ based local sensing of tissue parameters (e.g., temperature, force/pressure, thickness). As depicted in the bottom graph 1304, the generator is configured to re-adjust the energy delivered P₃ based on sensing of tissue parameters (e.g., temperature, force/pressure, thickness).

FIG. 24 illustrates a graph 1400 depicting one aspect of adjustment of threshold due to the measurement of a secondary tissue parameter such as continuity, temperature, pressure, and the like. The horizontal axis of the graph 1400 is time (t) and the vertical axis is tissue impedance (Z). The curve 1412 represents the change of tissue impedance (Z) over time (t) as different energy modalities are applied to the tissue. With reference also to FIGS. 20-22, the original threshold 1402 is applied when tissue is detected in all five segments 1-5 (tissue zones 1-5) and the adjusted threshold 1404 is applied when the tissue is detected in tissue segments 1-3 (tissue zones 1-3). Accordingly, once the tissue is located in particulars segments (zones) the control circuit in the generator adjusts the threshold accordingly.

As shown in FIG. 24, the curve 1412 includes three separate sections 1406, 1408, 1410. The first section 1406 of the curve 1412 represents the time when RF energy is applied to the tissue in tissue zones 1-3 until the tissue impedance drops below the adjusted threshold 1404. At that point 1414, which may indicate that a tissue seal is completed, the energy modality applied to tissue zones 1-3 is changed from RF energy to ultrasonic energy. The ultrasonic energy is then applied in the second and third sections 1408, 1410 and the impedance rises exponentially until the tissue is severed or cut.

FIG. 25 is a cross-sectional view of one aspect of a flexible circuit 1500 comprising RF electrodes and data sensors embedded therein. The flexible circuit 1500 can be mounted to the right or left portion of an RF clamp arm 1502, which is made of electrically conductive material such as metal. Below the RF clamp arm 1502 down force/pressure sensors 1506 a, 1506 b are embedded below a laminate layer 1504. A transverse force/pressure sensor 1508 is located below the down force/pressure sensor 1506 a, 1506 b layer and a temperature sensor is 1510 is located below the transverse force/pressure sensor 1508. An electrode 1512 electrically coupled to the generator and configured to apply RF energy to the tissue 1514 is located below the temperature sensor 1510.

FIG. 26 is a cross-sectional view of one aspect of an end effector 1600 configured to sense force or pressure applied to tissue located between a clamp arm and an ultrasonic blade. The end effector 1600 comprises a clamp jaw 1602 and a flexible circuit 1604 fixedly mounted to the clamp arm 1602. The clamp arm 1602 applies forces F₁ and F₂ to the tissue 1606 of variable density and thickness, which can be measure by first and second force/pressure sensors 1608, 1610 located in different layers of the flexible circuit 1604. A compressive layer 1612 is sandwiched between the first and second force/pressure sensors 1608, 1610. An electrode 1614 is located on outer portion of the flexible circuit 1604 which contacts the tissue. As described herein, other layers of the flexible circuit 1604 may comprise additional sensors such temperature sensors, thickness sensors, and the like.

FIGS. 27-29 illustrate various schematic diagrams of flexible circuits of the signal layer, sensor wiring, and an RF energy drive circuit. FIG. 27 is a schematic diagram of one aspect of a signal layer of a flexible circuit 1700. The flexible circuit 1700 comprises multiple layers (˜4 to −6, for example). One layer will supply the integrated circuits with power and another layer with ground. Two additional layers will carry the RF power RF1 and RF2 separately. An analog multiplexer switch 1702 has eight bidirectional translating switches that can be controlled through the I²C bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of a programmable control register. The upstream pairs SCL/SDA are connected to a control circuit in the generator. There are six down stream sensors, three on each side of the clamp arm. A first side 1704 a comprises a first thermocouple 1706 a, a first pressure sensor 1708 a, and a first Hall effect sensor 1710 a. A second side 1704 b comprises a second thermocouple 1706 b, a second pressure sensor 1708 b, and a second Hall effect sensor 1710 b. FIG. 28 is a schematic diagram 1750 of sensor wiring for the flexible circuit 1700 shown in FIG. 27.

FIG. 29 is a schematic diagram of one aspect of an RF energy drive circuit 1800. The RF energy drive circuit 1800 comprises an analog multiplexer 1702 described in connection with FIG. 27. The analog multiplexer multiplexes various signals from the upstream channels SCL/SDA. A current sensor 1802 is coupled in series with the return or ground leg of the power supply circuit to measure the current supplied by the power supply. An FET temperature sensor 1804 provided the ambient temperature. A pulse width modulation (PWM) watchdog timer 1808 automatically generates a system reset if the main program neglects to periodically service it. It is provided to automatically reset the RF energy drive circuit 1800 when it hangs because of a software or hardware fault.

A drive circuit 1806 provides left and right RF energy outputs. The digital signal is provided to the SCL/SDA inputs of the analog multiplexer 1702 from a control circuit of the generator. A digital-to-analog converter (DAC) converts the digital input to an analog output to drive a pulse width modulation (PWM) circuit 1812 coupled to an oscillator 1814. The PWM circuit 1812 provides a first gate drive signal 1816 a to a first transistor output stage 1818 a to drive a first RF (Left) energy output. The PWM circuit 1812 also provides a second gate drive signal 1816 b to a second transistor output stage 1818 to drive a second RF (Right) energy output.

The circuits 1700, 1750, 1800 described in connection with FIGS. 27-29 are electrically coupled to the generators 200, 300, 400, 500 shown in FIGS. 5-7. For example, the circuits 1700, 1750, 1800 may be coupled to the generator 200 via the signal conditioning circuit 244 and may be coupled to the generator 500 through the interface circuit 520.

FIG. 30 is a graphical representation 1900 of measuring tissue gap at a preset time. A first graph 1902 represents tissue impedance Z versus time (t) where the horizontal axis represents time (t) and the vertical axis represents tissue impedance Z. A second graph 1904 represents change in tissue gap Δ_(gap) versus time (t) where the horizontal axis represents time (t) and the vertical axis represents change in tissue gap Δ_(gap). A third graph 1906 represents force F versus time (t) where the horizontal axis represents time (t) and the vertical axis represents force F. Wth a constant force F applied to tissue and impedance Z interrogation to define a wait period, energy modality (e.g., RF and ultrasonic) and motor control parameters, displacement at a time provides velocity. With reference to the three graphs 1902, 1904, 1906, impedance sensing energy is applied during a first period 1908 to determine the tissue type such as thin mesentery tissue (solid line), intermediate thickness vessel tissue (dashed line), or thick uterus/bowel tissue (dash-dot line).

As shown in the third graph 1906, the clamp arm initially applies a force which ramps up from zero exponentially until it reaches a constant force 1924. The preset time t₁ is selected such that it occurs some time after the clamp arm force reaches a constant force 1924. As shown in the first and second graphs 1902, 1904, from the time the clamp force is applied to the mesentery tissue until the preset time t₁ is reached, the change in tissue gap Δ_(gap) curve 1912 decreases exponentially and the tissue impedance curve 1918 also decreases until the preset time t₁ is reached. From the preset time t₁, a short delay 1928 is applied before treatment energy is applied to the mesentery tissue at t_(E1).

As shown in the first and second graphs 1902, 1904, from the time the clamp force is applied to the vessel tissue until the preset time t₁ is reached, the change in tissue gap Δ_(gap) curve 1916 also decrease exponentially and the tissue impedance curve 1920 also decreases until the preset time t₁ is reached. From the preset time t₁, a medium delay 1930 is applied before treatment energy is applied to the vessel tissue at t_(E2).

As shown in the first and second graphs 1902, 1904, from the time the clamp force is applied to the uterus/bowel tissue until the preset time t₁ is reached, the change in tissue gap Δ_(gap) curve 1914 drops exponentially and the tissue impedance curve 1914 also drops until the preset time t₁ is reached. From the preset time t₁, a short delay 1928 is applied before treatment energy is applied to the mesentery tissue at t_(E1).

FIG. 31 is a time to preset force 2008 versus time graph 2000 for thin, medium, and thick tissue types. The horizontal axis represents time (t) and the vertical axis represents force (F) applied by the clamp arm to the tissue. The graph 2000 depicts three curves, one for thin tissue 2002 shown in solid line, one for medium thickness tissue 2004 shown in dash-dot line, and thick tissue 2006 in dashed line. The graph 2000 depicts measuring time at a preset force as an alternative to tissue gap to control delayed energy mode and other control parameters. Accordingly, the time to preset force 2008 for thick tissue 2006 is t_(1a), the time to preset force 2008 for medium thickness tissue 2004 is t_(1b), and the time to preset force 2008 for thin tissue 2002 is t_(1c).

Once the force reaches the preset force 2008, energy is applied to the tissue. For thin tissue 2002 the time to preset t_(1c)>0.5 seconds and then RF energy is applied for an energizing period t_(e) of about 1-3 seconds. For thick tissue 2006 the time to preset t_(1a)<0.5 seconds and then RF energy is applied for an energizing period t_(e) of about 5-9 seconds. For medium thickness tissue 2004 the time to preset t_(1b) is about 0.5 seconds and then RF energy is applied for an energizing period t_(e) of about 3 to 5 seconds.

FIG. 32 is a graphical depiction of a graph 2100 of three curves 2102, 2104, 2106, where the first curve 2102 represents power (P), voltage (V_(RF)), and current (I_(RF)) versus tissue impedance (Z), the second curve 2104 and third curve 2106 represent tissue impedance (Z) versus time (t). The first curve 2102 illustrates the application of power (P) for thick tissue impedance range 2110 and thin tissue impedance range 2112. As the tissue impedance Z increases, the current I_(RF) decrease and the voltage V_(RF) increases. The power curve P increases until it reaches a maximum power output 2108 which coincides with the intersection 2114 of the current I_(RF) and voltage V_(RF) curves.

The second curve 2104 represents the measured tissue impedance Z versus time (t). The tissue impedance threshold limit 2120 is the cross over limit for switching between the RF and ultrasonic energy modalities. For example, as shown in FIG. 32, RF energy is applied while the tissue impedance is above the tissue impedance threshold limit 2120 and ultrasonic energy 2124 is applied while the tissue impedance is below the tissue impedance threshold limit 2120. Accordingly, with reference back to the second curve 2104, the tissue impedance of the thin tissue curve 2116 remains above the tissue impedance threshold limit 2120, thus only RF energy modality is applied to the tissue. On the other hand, RF energy modality is applied to the tick tissue while the impedance is above the tissue impedance threshold limit 2120 and ultrasonic energy is applied to the tissue when the impedance is below the tissue impedance threshold limit 2120. Accordingly, the energy modality switches from RF to ultrasonic when the tissue impedance falls below the tissue impedance threshold limit 2120 and the energy modality switches from ultrasonic to RF when the tissue impedance rises above the tissue impedance threshold limit 2120.

FIG. 33 is a plan view of one aspect of an end effector 2200. The end effector 2200 comprises a clamp arm 2202 and a shaft 2204. The clamp arm 2202 pivots about pivot point 2206 and defines a pivot angle. FIG. 34 is a side view of the end effector 2200 shown in FIG. 33 with a partial cut away view to expose the underlying structure of the clamp arm 2202 and an ultrasonic blade 2208. An electrode 2210 is fixedly mounted to the clamp arm 2202. The electrode 2210 is electrically coupled to the generator and is configured to apply RF energy to tissue located between the clamp arm 2202 and the ultrasonic blade 2208. FIG. 35 is partial sectional view of the end effector shown in FIGS. 33, 34 to expose the ultrasonic blade and right and left electrodes 2210 a, 2210 b, respectively.

FIG. 36 is a cross-sectional view taken at section 36-36 of the end effector 2200 shown in FIG. 33. The end effector 2200 comprises an ultrasonic blade 2208 acoustically coupled to an ultrasonic transducer which is electrically driven by the generator. The clamp arm 2202 comprises an electrode 2210 a on the right side and an electrode 2210 b on the left side (from the perspective of the operator). The right side electrode 2210 a defines a first width W₁ and defines a first gap G₁ between the electrode 2210 a and the ultrasonic blade 2208. The left side electrode 2210 b defines a second width W₂ and defines a second gap G₂ between the electrode 2210 b and the ultrasonic blade 2208. In one aspect the first width W₁ is less than the second width W₂ and the first gap G₁ is less than the second gap G₂. Wth reference also to FIG. 35, a soft polymeric pad 2212 is located between the ultrasonic blade 2208 and the clamp arm 2202. A high density polymeric pad 2214 is located adjacent the soft polymeric pad 2212 to prevent the ultrasonic blade 2208 from shorting the electrodes 2210 a, 2210 b. In one aspect, the soft polymeric pads 2212, 2214 can be made of polymers known under the tradename TEFLON (polytetrafluoroethylene polymers and copolymers), for example.

FIG. 37 is cross-sectional view taken at section 37-37 of the end effector 2200 shown in FIG. 33. At the plane where section 37-37 the end effector 2200 is thinner and has more curvature than section 36-36. The right side electrode 2210 a defines a third width W₃ and defines a third gap G₃ between the electrode 2210 a and the ultrasonic blade 2208. The left side electrode 2210 b defines a fourth width W₄ and defines a fourth gap G₄ between the electrode 2210 b and the ultrasonic blade 2208. In one aspect the third width W₃ is less than the fourth width W₄ and the third gap G₃ is less than the fourth gap G₄.

FIG. 38 is a cross-sectional view taken at section 36-36 of the end effector 2200 shown in FIG. 33, except that the ultrasonic blade 2208′ has a different geometric configuration. The end effector 2200′ comprises an ultrasonic blade 2208′ cacoustically coupled to an ultrasonic transducer which is electrically driven by the generator. The clamp arm 2202′ comprises an electrode 2210 a′ on the right side and an electrode 2210 b′ on the left side (from the perspective of the operator). The right side electrode 2210 a′ defines a first width W₁ and defines a first gap G₁ between the electrode 2210 a′ and the ultrasonic blade 2208′. The left side electrode 2210 b′ defines a second width W₂ and defines a second gap G₂ between the electrode 2210 b′ and the ultrasonic blade 2208′. In one aspect the first width W₁ is less than the second width W₂ and the first gap G₁ is less than the second gap G₂. A high density polymeric pad 2214′ is located adjacent the soft polymeric pad 2212′ to prevent the ultrasonic blade 2208′ from shorting the electrodes 2210 a′, 2210 b′. In one aspect, the soft polymeric pads 2212′, 2214′ can be made of polymers known under the tradename TEFLON (polytetrafluoroethylene polymers and copolymers), for example.

FIG. 39 is cross-sectional view taken at section 37-37 of the end effector 2200 shown in FIG. 33, except that the ultrasonic blade 2208′ has a different geometric configuration. At the plane where section 37-37 the end effector 2200′ is thinner and has more curvature than the end effector 2200′ at section 36-36. The right side electrode 2210 a′ defines a third width W₃ and defines a third gap G₃ between the electrode 2210 a′ and the ultrasonic blade 2208′. The left side electrode 2210 b′ defines a fourth width W₄ and defines a fourth gap G₄ between the electrode 2210 b′ and the ultrasonic blade 2208′. In one aspect the third width W₃ is less than the fourth width W₄ and the third gap G₃ is less than the fourth gap G₄.

FIG. 40 is a cross-sectional view taken at section 36-36 of the end effector 2200 shown in FIG. 33, except that the ultrasonic blade 2208″ has a different geometric configuration. The end effector 2200″ comprises an ultrasonic blade 2208″ cacoustically coupled to an ultrasonic transducer which is electrically driven by the generator. The clamp arm 2202″ comprises an electrode 2210 a″ on the right side and an electrode 2210 b″ on the left side (from the perspective of the operator). The right side electrode 2210 a″ defines a first width W₁ and defines a first gap G₁ between the electrode 2210 a″ and the ultrasonic blade 2208″. The left side electrode 2210 b″ defines a second width W₂ and defines a second gap G₂ between the electrode 2210 b″ and the ultrasonic blade 2208″. In one aspect the first width W₁ is less than the second width W₂ and the first gap G₁ is less than the second gap G₂. A high density polymeric pad 2214″ is located adjacent the soft polymeric pad 2212″ to prevent the ultrasonic blade 2208″ from shorting the electrodes 2210 a″, 2210 b″. In one aspect, the polymeric pads 2212″, 2214″ can be made of polymers known under the tradename TEFLON (polytetrafluoroethylene polymers and copolymers), for example.

FIG. 41 is cross-sectional view taken at section 37-37 of the end effector 2200 shown in FIG. 33, except that the ultrasonic blade 2208″ has a different geometric configuration. At the plane where section 37-37 the end effector 2200″ is thinner and has more curvature than the end effector 2200″ at section 36-36. The right side electrode 2210 a″ defines a third width W₃ and defines a third gap G₃ between the electrode 2210 a″ and the ultrasonic blade 2208″. The left side electrode 2210 b″ defines a fourth width W₄ and defines a fourth gap G₄ between the electrode 2210 b″ and the ultrasonic blade 2208″. In one aspect the third width W₃ is less than the fourth width W₄ and the third gap G₃ is less than the fourth gap G₄.

The surgical instruments described herein also can include features to allow the energy being delivered by the generator to be dynamically changed based on the type of tissue being treated by an end effector of a surgical instrument and various characteristics of the tissue. In one aspect, a technique for controlling the power output from a generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), that is delivered to the end effector of the surgical instrument can include an input that represents the tissue type to allow the energy profile from the generator to be dynamically changed during the procedure based on the type of tissue being effected by the end effector of the surgical instrument.

As disclosed herein, techniques for controlling a generator based on the tissue type may be provided. Various techniques can be used to select a power profile to allow the energy being delivered from the generator to dynamically change based on the tissue type being treated by the surgical instrument.

FIG. 42A illustrates an end effector 2300 comprising a clamp arm 2302 and an ultrasonic blade 2304, where the clamp arm 2302 includes electrodes 2306. The end effector 2300 can be employed in one of the surgical instruments 104, 106, 108 referred to in FIGS. 1-3. In addition to the end effector 122, 124, 125, the surgical instruments 104, 106, 108 include a handpiece 105, 107, 109 and a shaft 126, 127, 129, respectively. The end effectors 122, 124, 125 may be used to compress, cut, and/or seal tissue. Referring to FIG. 42A, the end effector 2300, similar to the end effectors 122, 124, 125 shown in FIGS. 1-3, may be positioned by a physician to surround tissue 2308 prior to compression, cutting, or stapling. As shown in FIG. 42A, no compression may be applied to the tissue while preparing to use the end effector 2300. As shown in FIG. 42A, the tissue 2308 is not under compression between the clamp arm 2302 and the ultrasonic blade 2304.

Referring now to FIG. 42B, by engaging the trigger on the handle of a surgical instrument, the physician may use the end effector 2300 to compress the tissue 2308. In one aspect, the tissue 2308 may be compressed to its maximum threshold, as shown in FIG. 42B. As shown in FIG. 42A, the tissue 2308 is under maximum compression between the clamp arm 2302 and the ultrasonic blade 2304.

Referring to FIG. 43A, various forces may be applied to the tissue 2308 by the end effector 2300. For example, vertical forces F1 and F2 may be applied by the clamp arm 2302 and the ultrasonic blade 2304 of the end effector 2300 as tissue 2308 is compressed between the two. Referring now to FIG. 43B, various diagonal and/or lateral forces also may be applied to the tissue 2308 when compressed by the end effector 2300. For example, a force F3 may be applied. For the purposes of operating a medical device such as the surgical instruments 104, 106, 108 it may be desirable to sense or calculate the various forms of compression being applied to the tissue by the end effector. For example, knowledge of vertical or lateral compression may allow the end effector to more precisely or accurately apply a staple operation or may inform the operator of the surgical instrument such that the surgical instrument can be used more properly or safely.

In one form, a strain gauge can be used to measure the force applied to the tissue 2308 by the end effector shown in FIGS. 42A-B and 43A-B. A strain gauge can be coupled to the end effector 2300 to measure the force on the tissue 2308 being treated by the end effector 2300. Wth reference now also to FIG. 44, in the aspect illustrated in FIG. 44, a system 2400 for measuring forces applied to the tissue 2308 comprises a strain gauge sensor 2402, such as, for example, a micro-strain gauge, is configured to measure one or more parameters of the end effector 2300 such as, for example, the amplitude of the strain exerted on a clamp arm of an end effector, such as the clamp arm 2302 of FIGS. 43A-B, during a clamping operation, which can be indicative of the tissue compression. The measured strain is converted to a digital signal and provided to a processor 2410 of a microcontroller 2408. A load sensor 2404 can measure the force to operate the ultrasonic blade 2304 to cut the tissue 2308 captured between the clamp arm 2302 and the ultrasonic blade 2304 of the end effector 2300. A magnetic field sensor 2406 can be employed to measure the thickness of the captured tissue 2308. The measurement of the magnetic field sensor 2406 also may be converted to a digital signal and provided to the processor 2410.

Further to the above, a feedback indicator 2414 also can be configured to communicate with the microcontroller 2408. In one aspect, the feedback indicator 2414 can be disposed in the handle of a surgical instrument, such as those shown in FIGS. 1-3. Alternatively, the feedback indicator 2414 can be disposed in a shaft assembly of a surgical instrument, for example. In any event, the microcontroller 2408 may employ the feedback indicator 2414 to provide feedback to an operator of the surgical instrument with regard to the adequacy of a manual input such as, for example, a selected position of a firing trigger that is used to cause the end effector to clamp down on tissue. To do so, the microcontroller 2408 may assess the selected position of the clamp arm 2302 and/or firing trigger. The measurements of the tissue 2308 compression, the tissue 2308 thickness, and/or the force required to close the end effector 2300 on the tissue, as respectively measured by the sensors 2402, 2404, 2406, can be used by the microcontroller 2408 to characterize the selected position of the firing trigger and/or the corresponding value of the speed of end effector. In one instance, a memory 2412 may store a technique, an equation, and/or a look-up table which can be employed by the microcontroller 2408 in the assessment.

The generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), surgical instruments 104, 106, 108 (FIGS. 1-3), and end effectors 122, 124, 125, 700, 800, 900, 1000, 1100, 1200, 2200, 2200′, 2200″, 2300 (FIGS. 1-3, 14-22, 33-43B) described herein may be employed alone or in combination to perform surgical procedures in accordance with the techniques and processes described hereinbelow. Nevertheless, for conciseness and clarity, the surgical procedures are described with reference to the multifunction surgical instrument 108 and the generator 500. The multifunction surgical instrument 108 comprises an end effector 125 which includes a clamp arm 145 and an ultrasonic blade 149. The end effector 125 may be configured with any of the structural or functional features of any one of the end effectors 122, 124, 125, 700, 800, 900, 1000, 1100, 1200, 2200, 2200′, 2200″, 2300 to provide electrodes to apply RF energy to tissue, temperature sensors, force/pressure sensors, and gap measurement sensors, as described hereinabove.

Techniques for Determining Tissue Coefficient of Friction/Tissue Coefficient of Coagulation

In one aspect, the present disclosure provides a technique for determining a tissue coefficient of friction/tissue coefficient of coagulation to control the power output from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). The power delivered to an end effector of a surgical instrument can vary based on a tissue coefficient of friction. The energy profile from the generator can be adjusted based on the tissue coefficient of friction and dynamically switched during the procedure between RF and ultrasonic energy modalities based on the tissue impedance to treat the tissue clamped between a clamp arm and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for determining a tissue coefficient of friction will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The following description provides techniques for determining a tissue coefficient of friction μ. In order to accurately calculate the tissue coefficient of friction μ of the tissue 2308, the force applied to the tissue 2308 must be in a certain range to ensure that there is sufficient contact between the tissue 2308 and the end effector 2300 and that therapeutic amounts of energy are being delivered to the end effector 2300. For example, in one aspect, a minimum load on the tissue 2308 can be 1.5 lbs. to ensure that there is enough contact between the tissue 2308 and the end effector 2300, and a maximum load on the tissue 2308 can be 2.2 lbs. to ensure that a therapeutic amount of energy is being used. These values can be used with a power level 1. In addition, the force is measured using any of the above measurement components and techniques at various loads on the tissue 2308. At least two measurements can be taken at two different loads. For example, power can be measured at 1.76 lbs. (800 grams) and 2.2 lbs. (1000 grams) in order to graph power versus force. It can be more accurate, however, to take measurements at a plurality of loads and store the values in a buffer. In one form, a buffer can be filled with values for each incremental gram between 2400 grams and 1000 grams and can use various rules, such as the first in first out rule, to store the values until the slope value is maximized. A new regression can be performed each time a new value is added to the buffer and a value is dropped from the buffer. Various other methods can be used as well to calculate the slope value.

A functional model for heating of tissue can be represented in a simple frictional model:

{dot over (Q)}=μ·ν·N  Equation 1

where {dot over (Q)} is the rate of heat generation, ν is the rms velocity of the ultrasonic motion at the tip of the blade, and N is the normal force driving tissue against the ultrasonic blade. The tissue coefficient of friction, μ, is the proportionality constant that makes the statement true and it relates to tissue properties. It is therefore referred to as the tissue coefficient of friction μ and may be referred to interchangeably as the tissue coefficient of coagulation. As is known in the art, friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

In practice, {dot over (Q)} is the measured amount power equal to the product of the rms values of current and voltage when driven at zero phase. The velocity is the product of the rms displacement, d, times the radian frequency or ν=2πf·d. In the case of an ultrasonic surgical system this is the frequency at resonance which equals 55.5 kHz for the ultrasonic system. Furthermore d is proportional to the current driving the system, which is set by the level on the generator. The factor ν is readily calculated. N is the normal force which is either set by the instrument design at full trigger closure or can be measured with a force gage/strain gage. Since {dot over (Q)}, ν, and N are calculable from known parameters, then can be estimated by rearranging Equation 1:

$\mu = \frac{\overset{.}{Q}}{v \cdot N}$

Note that removing the quiescent power from {dot over (Q)} and updating the frequency f as the resonance drifts lower, will increase the repeatability and accuracy of the estimated tissue coefficient of friction μ. In order to determine the type of tissue being treated by the end effector of the surgical instrument, a tissue coefficient of friction μ can be calculated. The calculated tissue coefficient of friction is compared to a database of tissue coefficients of friction that correlates each tissue coefficient of friction with a tissue type, as will be discussed in more detail below. The calculated tissue coefficient of friction and its related tissue type are used by a technique to control the energy being delivered from the generator to the surgical instrument. In one form, the tissue coefficient of friction μ is described by the above where {dot over (Q)} is the rate of heat generation, ν is the velocity of the ultrasonic motion of the end effector, and N is the force applied to the tissue by the end effector. The velocity ν of the ultrasonic motion is a known value from the settings of the generator. Since the value ν is a known value, the tissue coefficient of friction μ can be calculated using the slope of a graph of heat generation versus force on the tissue.

The force applied to the tissue by the end effector can be measured in a variety of ways using different type of components to measure force. This force measurement can be used, for example in the equation above, to determine the tissue coefficient of friction of the tissue being treated to determine its tissue type.

Looking at the equation {dot over (Q)}=μ·ν·N the product of the tissue coefficient of friction and velocity, μ·ν, is the slope of the relation of heat generation and normal load. Because ν is known, μ can be determined by the slope of a graph of heat generation versus normal load. An example of a graph 2500 of power (Watts) shown along the vertical axis versus force (g) shown along the horizontal axis as measured with a plurality of plotted data points is illustrated in FIGS. 45-46. FIG. 45 illustrates graphs 2500 for a porcine carotid curves 2502, 2504 at two different power levels, porcine bowel curve 2506, and dry chamois curve 2508. The data for a carotid artery at Level 3 is also shown. These are single measurements and there are no means and standard deviations to test for differences. While ideally the values of the tissue coefficient of friction μ at Levels 1 and 3 should be the same, the values at 0.30 and 0.35 are sufficiently close to believe that μ is an intrinsic property of the tissue.

FIG. 46 illustrates the same graphs 2500′ as FIG. 45, but only the sections of each graph that are substantially linear. The linear sections 2502′, 2504′, 2506′, 2508′ of each curve 2502, 2504, 2506, 2508 (FIG. 45) are located in the region of the curve where the force was greater than the initial low level of force used. Each of the linear sections 2502′, 2504′, 2506′, 2508′ can be modeled as a regression line in the form of:

y=mx+b  Equation 2

where y is the dependent variable (Power [Watts]), x is the independent variable (Force [g]), m is the slope of the line, and b is the y-intercept.

Each of the linear sections 2502′, 2504′, 2506′, 2508′ also are characterized by R-squared (R²), where R² is a statistical measure of how close the data are to the fitted regression line y. It is also known as the coefficient of determination, or the coefficient of multiple determination for multiple regression. The definition of R² is the percentage of the response variable variation that is explained by the linear model y. In other words:

R ²=Explained variation/Total variation

R² is always between 0 and 100% where 0% indicates that the model explains none of the variability of the response data around its mean and 100% indicates that the model explains all the variability of the response data around its mean. In general, the higher the R², the better the model fits the data.

In the example illustrated in FIG. 46, the regression line and R² for the linear section 2502′ representing porcine carotid tissue at power level 1 are:

y=0.0137x+0.2768

R ²=0.9902

The regression line and R² for the linear section 2504′ representing porcine carotid tissue at power level 3 are:

y=0.0237x+8.9847

R ²=0.978

The regression line and R² for the linear section 906′ representing bowel tissue at power level 1 are:

y=0.0085x+10.587

R ²=0.9147

The regression line and R² for the linear section 2508′ representing chamois tissue at power level 1 are:

y=0.034x+0.0735

R ²=0.9949

The calculated tissue coefficient of friction μ is compared to a database of tissue coefficients of friction that correlated each coefficient with a tissue type. For example, Table 1 includes example tissue coefficients of friction μ as calculated from the plots of power and force illustrated in FIGS. 45-46 for each of the porcine carotid curves 2502, 2504 at two different power levels, porcine bowel curve 2506, and dry chamois curve 2508.

TABLE 1 Coefficient of Tissue Type Power Level Friction μ Porcine carotid 1 0.30 Porcine carotid 3 0.35 Porcine bowel 1 0.19 Dry chamois 1 0.75

Assumptions: Ultrasonic bade amplitude is nominally 75 μm p-p at level 5 and the frequency f is 55.5 kHz. It will be appreciated that the power levels referenced above are specific to the LCS product and level 5 of the GEN11 generator available from Ethicon Endo-Surgery, Inc. that is compatible with devices known under the tradename HARMONIC and ENSEAL, also available from Ethicon Endo-Surgery, Inc.

It should be noted that the tissue coefficient of friction μ for the porcine carotid tissue at various power levels should be the same as the tissue coefficient of friction μ is a value intrinsic to the tissue. The values of 0.30 and 0.35 for the calculated tissue coefficients of friction μ are substantially close enough to show that the tissue coefficient of friction μ is intrinsic to the tissue itself.

One technique for determining the slope is to measure power delivered at two loads. Assuming Level 1 is used for this calculation, then the power could be measured at nominally 800 grams (1.76 lbs) and 1000 grams (2.2 lbs). However just using the two points can be inaccurate. It is better to fill a buffer of approximately 201 points for every gram in the 800 to 1000 gram range inclusive. The buffer could be slide advanced using a first-in-first-out (FIFO) rule until the R² value is maximized. A new regression would be performed each time a new point is added and an old point is dropped. Other schemes can be envisioned as well. The calculated slope is then compared with known values for specific tissue types. For example if the calculated slope is in the region of 0.30 to 0.35, then an artery is determined to be in the jaws. If the values are in the range of 0.15 to 0.20 then a section of bowel is determined to be in the jaws. In one technique, the R² value may be used as an indication of specificity. For example if R² is less than 0.90, for example, then an indication is given that a determination cannot be made. R² values in the range of 0.60 to 1.00 may be used to indicate that a determination of tissue type can be made and preferably tis threshold may be about 0.90.

In practice, sampling would be done on a time basis and both power and force would be sampled. These configurations are captured in the logic flow diagram of FIG. 47. The technique can be implemented in the generator software and/or the surgical instrument software.

It will be appreciated that using the averages for power and force at two positions can improve the accuracy of a two-point slope calculation. For accuracy it may be necessary to measure closure force (and moment) in addition to power.

The benefits of using the tissue coefficient of friction μ as a means to characterize tissue is discussed hereinbelow in connection with FIG. 48. Accordingly, the tissue coefficient of friction μ can be used to discriminate tissues and can be calculated using a technique for including steps to determine that a selection cannot be made.

FIG. 47 illustrates a logic flow diagram 2600 of one form of a method for dynamically changing the energy delivered to a surgical instrument based on a determination of tissue type being treated by the instrument. As described herein, the logic flow diagram 2600 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 2600 shown in FIG. 47, a characterization mode of the system is started by the processor 502 in which the type of tissue being treated by the surgical instrument is determined 2602 by the processor 502. The end effector 125 is positioned such that tissue is positioned within the clamp arm 145 and the ultrasonic blade 149 of the end effector 125. The clamp arm 145 is used to apply a force to the tissue. The force of the end effector 125 on the tissue is measured and compared 2604 by the processor 502 to a threshold minimum force. If the force applied to the tissue is below a minimum threshold force, the force applied to the tissue is increased 2606 and is again measured and compared 2604 by the processor 502 to the threshold minimum force.

Once the force on the tissue has reached the minimum threshold force, the processor 502 samples 2608 the force applied to the tissue and the power delivered to the end effector 125 by the generator 500 and saves 2612 the samples in a buffer. The processor 502 determines 2610 whether the buffer is full. Samples are saved 2612 in the buffer until the buffer is full, and then the processor 502 utilizes the samples to plot 2614 points on a graph of force versus power. This information is used by the processor 502 to calculate and store 2616 the slope and R² values in a database. See FIG. 46, for example, for a graphical representation of the linear sections of power versus force plots including the coefficient of determination R². Once stored in the database, the processor 502 compares the force values to a maximum force threshold and determines 2618 when the force reaches a maximum threshold value. Until the force reaches the maximum threshold value, the processor 502 continues along the NO branch and continues sampling 2608 the next samples of power and force. The processor 502 repeats until the force reaches the maximum threshold.

Once the force has reached the maximum threshold, the samples are no longer taken and stored and the processor 502 continues along the YES branch to select 2620 the slope with the highest R² value and to calculate the tissue coefficient of friction μ. Next, the processor 502 determines 2622 if the maximum slope value R² is greater than a predetermined threshold. If R² is less than the predetermined threshold, then the confidence level is low and the slope value cannot be used to calculate the tissue coefficient of friction μ and identify the tissue type and the processor 502 continues along the YES branch to display 2624 a message indicating that the tissue type has not been identified. In one aspect, the threshold may be selected in the range of 0.6 to 1.00 and may preferably be set to about 0.90, for example. In other aspects, the threshold may be selected using more sophisticated, statistical tests applied to determine the level confidence R². If R² is greater than or equal to the predetermined threshold, the calculated tissue coefficient of friction μ can be used to identify the tissue and the processor 502 continues along the NO branch where the processor 502 compares 2626 the calculated tissue coefficient of friction μ to a database 2628 of stored tissue coefficients of friction μ which the stored tissue coefficients of friction μ correspond to tissue types. The tissue type is selected 2630 and displayed and used to specify 2632 the power delivery profile for delivering energy from the generator 500 to the end effector 125 of the surgical instrument 108. Normal operation mode is entered 2634 such that the tissue type and related power delivery profile are used to control the end effector 125 for treating the tissue.

In one aspect, the tissue coefficient of friction μ and its rate may be employed to determine tissue type and power delivery profile. For example, It has been shown in preliminary work that μ is significantly different between porcine bowel, artery and chamois. Furthermore the μ values were initial flat but did change as time progressed presumably because of the temperature rise as heat was added. From these observations, μ can be used as a tissue differentiator and can be done at lower current to avoid rapid changes in μ when the purpose is to characterize the tissue. Also, another parameter of interest would be the rate of change of the tissue coefficient of friction μ for fixed conditions of {dot over (Q)}, ν, and N. It will be appreciated that {dot over (μ)} is not simply differentiating the equation

$\mu = \frac{\overset{.}{Q}}{v \cdot N}$

with respect time, because the change is due to changes in the tissue itself. For example the μ for chamois rapidly rises when heat is delivered compare with carotid arteries or bowel, because it is dry. The rate of change is likely dependent on the percentage of water content in the tissue. In one aspect, the present disclosure provides a technique to estimate both the tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction μ and compare them with table of know values stored in a database, for example. The tissue selection can be based on the values closet to the estimated values. The power delivery profile could then be optimize for that tissue and delivered to the surgical instrument 108. Estimating the tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction μ may be able to further differentiate tissue types. Another aspect of the present disclosure includes tracking the tissue coefficient of friction μ as the seal/transection progresses. Key changes in this parameter may signal a need to modify the power delivery profile.

FIG. 48 illustrates a logic flow diagram 2700 of another form of a method for dynamically changing the energy delivered to a surgical instrument 108 based on a determination of tissue type being treated by the surgical instrument 108. As described herein, the logic flow diagram 2700 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 2700 shown in FIG. 48 and the surgical system 100 of FIG. 1, the processor 502 initiates a power evaluation mode of the system to determine 2702 the power profile for the generator 500. The end effector 125 of the surgical instrument 108 is then engaged with the tissue to be treated and the end effector 125 of the surgical instrument 108 is activated 2704 with energy delivered from the generator 500. The tissue coefficient of friction μ and the processor 502 measures 2706 the rate of change (e.g., rate of rise) of the tissue coefficient of friction μ over a short period of time. The processor 502 compares 2708 the measured tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction μ to values stored in a tissue information database 2714.

If the system is in learning mode, in which the tissue information database 2714 information regarding tissue type and tissue coefficients of friction μ are being updated, the tissue type can be visually identified 2710. The processor 502 updates 2712 the tissue information database 2714 of tissue coefficient of friction μ and tissue type information to increase the accuracy of the tissue information database 2714.

If the system is not in learning mode, then the processor 502 selects 2716 a power delivery profile based on the determined tissue and surgical instrument type 2718 being used. During the treatment of the tissue, the processor 502 continues to calculate and monitor 2720 the tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction μ to allow the processor 502 to dynamically update the power delivery profile. If an error is found, the power delivery profile is modified 2724. The processor 502 then determines 2722 if the correct pattern of power and delivery profile is being used. If no error is found, the current power delivery profile continues 2726. Otherwise, the processor 502 modifies 2724 the power and delivery profile. The processor 502 continues the process of verification and correction of the power delivery profile during the entire surgical procedure to optimize the energy being delivered to the surgical instrument 108 based on the type of tissue being treated.

Techniques for Controlling a Generator Based on the Hydration Level of Tissue

In one aspect, the present disclosure provides a technique for controlling the power output from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). The power delivered to the end effector of the surgical instrument can be controlled based on the hydration level of the tissue to allow the energy profile from the generator to be dynamically changed based on the hydration level of the tissue being treated by the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for controlling the power output from a generator based on the hydration level of tissue will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

In order to determine the hydration level of the tissue being treated by the end effector 125 of the surgical instrument 108, the tissue coefficient of friction μ as described herein can be used. As explained above, a force measurement is taken using any of the methods described herein to calculate the tissue coefficient of friction μ to determine the hydration level of the tissue. The calculated tissue coefficient of friction μ is compared to a database of tissue coefficients of friction μ that correlate each tissue coefficient with a hydration level of the tissue. The calculated tissue coefficient of friction μ and its related tissue hydration level are used by the technique to control the energy being delivered from the generator 500 to the surgical instrument 108.

The hydration level of the tissue can be indicative of a variety of conditions within the tissue. During a coagulation cycle in which RF energy is being used to coagulate the tissue, a decrease in the tissue hydration level can indicate that the tissue is nearing the end of the coagulation cycle. In addition, the hydration level of the tissue can vary during the coagulation cycle such that the RF energy being delivered from the generator 500 can dynamically change during the coagulation cycle based on the calculated hydration levels during the cycle. For example, as a coagulation cycle progresses, the hydration level of the tissue will decrease such that the technique used to control the energy delivered from the generator 500 can decrease the power as the cycle progresses. Thus, the hydration level of the tissue can be an indicator of the progress through a coagulation cycle of the tissue by the end effector of the surgical instrument 108.

FIG. 49 illustrates a logic flow diagram 5900 of one form of a method for dynamically changing the energy delivered to a surgical instrument 108 based on a determination of the hydration level of tissue being treated by the surgical instrument 108. As described herein, the logic flow diagram 5900 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram 5900 shown in FIG. 49, the processor 502 determines the hydration level of the tissue by measuring the tissue coefficient of friction μ as described herein. Initially, the end effector 125 of the surgical instrument 108 is closed on tissue and the end effector 125 is activated 5902 with energy from the generator 500. The processor 502 measures 5904 the tissue coefficient of friction μ, as described herein. The processor 502 compares 5906 the tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction μ to values stored in a database to determine the hydration level of the tissue. The processor 502 selects 5908 a power delivery profile based on the hydration level of the tissue. The processor 502 monitors 5910 the tissue coefficient of friction μ and the rate of change of the tissue coefficient of friction it during treatment of the tissue to monitor the changes in the tissue hydration level. This allows the processor 502 to dynamically change 5912 the power delivery profile, such that power delivered from the generator 500 can dynamically change during tissue treatment.

Techniques for Switching Between RF and Ultrasonic Energy Based on Tissue Type

In another aspect, the present disclosure provides a technique for controlling energy delivered by a generator and/or a surgical instrument by dynamically switching between RF and ultrasonic energy. The technique includes controlling the power output from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In one aspect, RF and ultrasonic energy can be dynamically switched based on the type of tissue being treated by an end effector of a surgical instrument and various characteristics of the tissue. The power delivered to the end effector of the surgical instrument can include an input that represents the tissue type to allow the energy profile from the generator to be dynamically changed between RF and ultrasonic energy during the procedure based on the type of tissue being effected by the end effector of the surgical instrument. For conciseness and clarity of disclosure, techniques for dynamically switching between different energy modalities, such as, for example RF energy and ultrasonic energy, will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

In order to determine the type of tissue being treated by the end effector 125 of the surgical instrument 108, a tissue coefficient of friction μ and/or the rate of change of the tissue coefficient of friction μ can be calculated and compared to a database of tissue coefficient of friction μ that correlates each tissue coefficient of friction μ with a tissue type, as explained above. The calculated tissue coefficient of friction μ and its related tissue type are used by a technique to control the type (RF or ultrasonic) and power level of energy being delivered from the generator 500 to the surgical instrument 108. Tissue types include, without limitation, tissue with a muscular structure, tissue with a vascular structure, tissue with a thin mesentery structure.

FIG. 50 illustrates a logic flow diagram 2900 of one aspect of a method of dynamically changing the between RF energy delivered from the ENERGY2/RETURN output of the generator 500 and ultrasonic energy delivered from the ENERGY1/RETURN output of the generator 500 to the surgical instrument 108 based on a determination of tissue type being treated by the surgical instrument 108. As described herein, the logic flow diagram 2900 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 2900 shown in FIG. 50, the processor 502 initiates a characterization mode of the generator 500 to determine 2902 the type of tissue being treated by the surgical instrument 108. The end effector 125 is positioned such that tissue is positioned between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125. The end effector 1255 applies a force to the tissue. The force applied to the tissue by the end effector 125 is measured and compared 2904 by the processor 502 to a threshold minimum force. If the processor 502 determines that the force applied to the tissue is below a minimum threshold force, the force applied to the tissue is increased 2906. Once the force on the tissue has reached the minimum threshold force, the processor 502 samples 2908 the force applied to the tissue and the power delivered to the end effector 125 by the generator 500 and stores the samples in a buffer.

The processor 502 determines 2901 if the buffer is full. If the buffer is not full, the processor 502 enters 2912 the most recent samples into the buffer. If the buffer is full, the processor 502 enters the most recent samples into the buffer and drops 2914 the first point (e.g., FIFO method for organizing and manipulating a data buffer). The processor 502 calculates and stores 2916 the slope and R² values and the force is tested to determine 2918 if the force applied to the tissue is greater than a maximum force threshold. If the force applied to the tissue is not greater than the maximum threshold, the processor 502 samples 2908 the force applied to the tissue and the power delivered to the end effector 125 by the generator 500 and saves the samples in a buffer. The processor 502 repeats until the force applied to the tissue is greater than the maximum threshold. The processor 502 selects the slope with the highest R² and calculates 2920 the tissue coefficient of friction μ. If the processor 502 determines 2922 that R² is less than a predetermined threshold, the processor 502 continues along the YES branch and the system displays 2924 that the tissue type was not identified. If R² is greaten than or equal to the threshold, the processor 502 continues along the NO branch and compares 2926 the calculated tissue coefficient of friction μ to values stored in a tissue information database 2928.

In one aspect, the threshold may be selected in the range of 0.6 to 1.00 and may preferably be set to about 0.90, for example. In other aspects, the threshold may be selected using more sophisticated, statistical tests applied to determine the level confidence R². In one aspect, the threshold may be selected between 0.6 to 1.00 and may preferably be set to about 0.90. In other aspects, the threshold may be selected using more sophisticated, statistical tests applied to determine the level confidence R². The processor 502 then selects 2930 and displays the tissue type and specifies 2932 the power delivery profile for delivering either ultrasonic energy (ENERGY1/RETURN) or RF energy (ENERGY2/RETURN) from the generator 500 to the end effector 125 of the surgical instrument 108. Normal operation mode is entered 2934 such that the tissue type and related power delivery profile are used to control the end effector for treating the tissue. Using the tissue type determined in accordance with the logic flow diagram 2900, the processor 502 can provide optimized energy delivery for that particular tissue. Tissue types that are determined to be more vascular or muscular would require more RF energy at the beginning of the cycle to provide more sealing energy either before the application of the ultrasonic energy or at a higher ratio of RF vs. ultrasonic energy. And tissue types that are less vascular would require less RF energy at the beginning of the cycle and the system would change the energy delivery toward a cutting profile using ultrasonic energy. Energy may be applied to the tissue until the tissue meets or exceeds a predetermined threshold impedance, which may be referred to as the termination impedance, and which is the tissue impedance that corresponds to the impedance of tissue when the tissue seal is complete.

Techniques for Dynamically Changing the Energy Delivered from a Generator Based on Aperture Defined by the End Effector and Energy Parameters

In one aspect, the present disclosure provides a technique for dynamically changing the energy delivered from a generator based on an aperture defined by an end effector. According to one aspect, the techniques for dynamically changing the energy delivered from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). For conciseness and clarity of disclosure, techniques for dynamically changing energy delivered from a generator based on an aperture defined by an end effector and energy parameters will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The energy profile from the generator 500 can be dynamically changed during the procedure between RF and ultrasonic energy based on the aperture defined by the end effector 125 that is clamping on a tissue. This allows the generator 500 to switch from RF energy to ultrasonic energy based on the amount of clamping force exerted by the end effector 125 on the tissue being treated by the surgical instrument 108. The aperture defined by the clamp arm 145 is related to the creation of a proper coagulation seal, for example, when RF energy is being delivered from the generator 500 to the end effector 125 of the surgical instrument 108, such that RF energy should be used when there is a sufficient closure of the end effector 108 on the tissue. Thus, when the aperture defined by the end effector 108 is too large and there is not a sufficient clamping force exerted on the tissue for proper coagulation, only ultrasonic energy is delivered to the ultrasonic blade 149 of the end effector 125 through the ENERGY1/RETURN output of the generator 500.

For example, misleading information regarding various tissue measurements and/or characteristics can be transmitted to the generator 500 for use in the techniques for controlling the energy delivered depending on the aperture defined by the end effector 125. One such measurement that can be affected by the aperture defined by the end effector 125 is tissue impedance. Tissue impedance measured by an instrument as described herein will depend on several factors including the clamping force or pressure applied by the end effector 125 and the distance between electrodes in the case of RF energy or the clamp arm 145 aperture in the case of ultrasonic energy. Many techniques that determine the end of the coagulation cycle depend on the tissue impedance. A clamp arm 145 that is not fully closed on the ultrasonic blade 149 can lead to a tissue impedance determination that may not properly represent the condition of the tissue. An incorrect tissue impedance determination can lead to early termination of a coagulation cycle as the generator 500 may switch from RF to ultrasonic energy before a proper coagulation seal has been achieved. In one aspect, the tissue impedance may be determined by the processor 502 by dividing the output of the second voltage sensing circuit 524 coupled across the terminals labeled ENERGY2/RETURN by the output of the current sensing circuit 514 is disposed in series with the RETURN leg of the secondary side of the power transformer 508 as shown in FIG. 8. The outputs of the voltage sensing circuit 512 are provided to an isolation transformer and ADC 516 and the output of the current sensing circuit 514 is provided to another isolation transformer and ADC 518 to provide the voltage and current measurement is digital form to the processor 502.

The aperture defined by the end effector 125 can be determined using a variety of techniques. In various aspects, the aperture defined by the end effector 125 may be determined by detecting the pivot angle of the end effector 125. This can be accomplished using a potentiometer, a Hall effect sensor (in a manner described in connection with FIG. 19), an optical encoder, an optical IR sensor, an inductance sensor, or combinations thereof. In another aspect, the proximity of first and second components of an end effector is measured to determine the aperture defined by the end effector using, for example, the Hall effect sensor, an optical encoder, an optical IR sensor, an inductance sensor, or combinations thereof. In another aspect, the surgical instrument 108 may be configured to detect the aperture defined by the end effector 125 by measuring a change in a tissue impedance of the tissue interacting with the end effector. In another aspect, the surgical instrument 108 may be configured to detect the aperture defined by the end effector 125 by measuring a load applied by the end effector 125 on the tissue as ultrasonic energy is pulsed to the end effector 125. In another aspect, the surgical instrument 108 includes a switch or other mechanism for closing the end effector 125 that can detect the aperture defined by the end effector 125. In another aspect, the aperture defined by the end effector 125 may be determined based on linear displacement or stroke of the closure mechanism located either in the shaft 129 or the handle 109 of the surgical instrument 108. In another form, the aperture defined by the end effector 125 may be determined by the angular displacement of the trigger mechanism located in the handle 109 of the surgical instrument 108.

FIG. 51 is a logic flow diagram 3000 of one aspect of a technique for dynamically changing the energy delivered from a generator based on aperture defined by the end effector and energy parameters. As described herein, the logic flow diagram 3000 may be implemented in the generator 500, the surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram 3000 shown in FIG. 51 and the surgical system 100 of FIG. 1 with the combination electrosurgical and ultrasonic multifunction surgical instrument 108 and the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), the aperture defined by the end effector 125 is determined as described herein. Initially, the end effector 125 of the surgical instrument 108 is closed on tissue, as shown in FIGS. 42A-B, 43A-B, and the end effector 125 is activated 3002 with energy from the generator 500, for example. The aperture defined by the end effector 125 is determined 3004 by the processor 502 using any of the techniques described herein. Once the aperture defined by the end effector 125 is determined 3004, the processor 502 signals the waveform generator 504 to delivery energy from the generator 500 and controls switching the output of the generator 500 between RF energy ENERGY2 and ultrasonic energy (ENERGY1/RETURN) based on the determined aperture defined by the end effector 125. Accordingly, the processor 502 selects 3006 a power delivery profile based on the aperture defined by the end effector 125. The processor 502 continues to monitor 3008 the aperture defined by the end effector 125 during the tissue treatment process and dynamically changes 3010 the energy delivered from the generator 500 based on the changing aperture defined by the end effector 125.

In another aspect, a technique for controlling the power output from the generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or the surgical instrument 108, such as the surgical instrument 108 (FIGS. 1-3) that is delivered to the end effector 125 of the surgical instrument 108 can include an input that includes energy parameters based on an aperture defined by the end effector 125 of the surgical instrument 108. The energy profile from the generator 500 can be dynamically changed during the procedure between RF and ultrasonic energy using the energy parameters based on the aperture defined by the end effector 125 that is clamping on tissue as shown in FIGS. 42A-B, 43A-B. This allows the generator 500 to switch from RF energy ENERGY2 to ultrasonic energy (ENERGY1/RETURN) based on the clamping force applied by the end effector 125 to the tissue being treated by the surgical instrument 108. As explained above, the aperture defined by the clamp arm 145 is related to creating a proper coagulation seal, for example, when RF energy is being delivered from the generator 500 to the end effector 125 of the surgical instrument 108, such that RF energy should be used when there is a sufficient closure of the end effector 125 on the tissue. Thus, when the aperture defined by the end effector 125 is too large and the clamping force applied to the tissue is insufficient for proper coagulation, only ultrasonic energy is delivered to the end effector 125 by the generator 500.

The aperture defined by the end effector 125 can be determined using any of the methods described herein. For example, the surgical instrument 108 can include an aperture defined by a sensor located in the end effector 125 that can be fed through a connector to the ASIC in the handle 109 of the surgical instrument 108. The surgical instrument 108 also can include a sensor in the handle 109 of the surgical instrument 108 that is configured to detect the aperture defined by the end effector 125.

Energy parameters are configured to be loaded into the generator 500, and can include a plurality of different parameters, including but not limited to voltage, current, power, and one or more techniques for use in treating tissue. These parameters can be related to the RF energy and ultrasonic energy that can be delivered from the generator 500. The energy parameters can include information such as maximum and/or minimum values to be used to control the energy delivered from the generator 500. The energy parameters can be stored in a variety of locations, including an EEPROM on the surgical instrument or some other non-volatile memory. In addition, there can be multiple sets of energy parameters. For example, there can be a first set of energy parameters that are used to optimize tissue transection, and a second set of energy parameters that are used to optimize tissue spot coagulation. It will be understood that there can be any number of set of energy parameters that correspond to various types of tissue treatments to allow the generator to switch between the various sets of energy parameters based on the necessary tissue treatments.

When the end effector 125 of the surgical instrument 108 is activated, one or more of the various techniques described herein are used to detect the aperture defined by the end effector 108. In one aspect, when the end effector 125 is closed around the tissue, the generator 500 can utilize the energy parameters for optimizing tissue transection. When the end effector 125 has a larger aperture and is not clamped on the tissue, the generator 500 can utilize the energy parameters for optimizing spot coagulation of the tissue.

FIG. 52 is a logic flow diagram 3200 of one aspect of a technique for dynamically changing the energy delivered from a generator based on aperture defined by the end effector and energy parameters. As described herein, the logic flow diagram 3200 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3100 shown in FIG. 52, with the combination electrosurgical and ultrasonic instrument 108 and the generator 500, initially the aperture defined by the end effector 125 is determined by the processor 502 as described herein. The end effector 125 of the surgical instrument 108 is closed on tissue, as shown in FIGS. 42A-B, 43A-B, and the end effector 125 is activated with energy from the generator 500. The aperture defined by the end effector 125 is determined 3104 using any of the techniques described herein. The processor 502 signals the waveform generator 504 to deliver energy from the generator 500 to the end effector 125 and switch the generator 500 output between to switch between RF and ultrasonic energy based on the aperture defined by the end effector 125 by using one of the sets of energy parameters that was previously loaded into the generator 500. Accordingly, energy parameters are communicated 3106 to the generator 500 based on the previously determined 3104 aperture defined by the end effector 125. The processor 502 monitors 3108 the aperture defined by the end effector 125 during the tissue treatment process such that the energy delivered from the generator 500 can be dynamically communicated 3110 by the processor 502 during the tissue treatment process based on the changing aperture defined by the end effector 125. This allows the generator 500 to dynamically switch between the various sets of energy parameters based on the changing aperture defined by the end effector 125.

It will be understood that various combinations of information can be used to determine which set of energy parameters are to be used during tissue treatment. For example, the aperture defined by the end effector and calculated tissue impedance can be used to determine which set of energy parameters are needed to control the energy being delivered from the generator.

Techniques for Dynamic Sensing of Tissue

In one aspect, the present disclosure provides dynamic tissue sensing techniques. In one aspect, the dynamic tissue sensing techniques may be implemented with a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). For conciseness and clarity of disclosure, the dynamic tissue sensing techniques will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

Upon measuring the tissue thickness and the normal force on the ultrasonic blade as shown in and described in connection with FIGS. 42A-B, 43A-B, and measuring the tissue coefficient of friction μ, in one aspect a technique is provided that pulses to measure the tissue coefficient of friction μ at set time intervals and based on the measured coefficient μ over time, adjusts the power delivered by any one of and the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or the surgical instrument (FIGS. 1-3), in order to transect or “cut” tissue efficiently and with good hemostasis. In one aspect, a sensing technique is configured to monitor tissue friction and determine the tissue coefficient of friction μ, as described herein, throughout a cut and modulates energy delivered during the cut based on change in the tissue coefficient of friction μ over time.

FIG. 53 is a logic flow diagram 3200 of one aspect of a dynamic tissue sensing technique. As described herein, the logic flow diagram 3200 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3200 shown in FIG. 53, case specific details for knowledge of tissue type are input 322 into the generator 500. The end effector 125 of the surgical instrument 108 is closed on the tissue, as shown in FIGS. 42A-B, 43A-B, and the tissue coefficient of friction μ is checked 3204 by the processor 502 and power is delivered 3206 to the tissue according to known normal force N, tissue coefficient of friction and tissue thickness as determined by processor 502 as described herein. The processor 502 compares 3208 the rate of change of μ/|μ| to known values of μ. In one aspect, a look-up table for predefined μ/Power Delivery Ratios may be utilized by the processor 502. The processor 502 adjusts 3210 the power delivered by the generator 500 higher or lower based on Δμ. When μ reaches 3212 a known or predetermined threshold, the processor 502 checks 3214 the clamp arm 145 of the end effector 125 for closure against the ultrasonic blade 149. In one aspect, this can be determined based on known normal force N and known production normal force N_(p) that represents a closed end effector jaw. When the jaw closure is complete, the processor 502 control the delivery 3216 of short bursts of power to complete the tissue transection or cut until the cut is completed 3218.

Accordingly, by measuring the tissue coefficient of friction the processor 502 pulses to measure the tissue coefficient of friction μ at set time intervals and based on the measured coefficient μ over time, and adjusts the power delivered by generator 500 to the tissue in order to transect or “cut” tissue efficiently and with good hemostasis. In one aspect, the sensing technique monitors and periodically determines the tissue coefficient of friction as described herein, while making the cut and modulates the energy delivered by the generator during the cut based on change in the tissue coefficient of friction Δμ over time.

Techniques for Sealing or Sealing and Cutting Lame Vessels and Tissue-Bundles

In one aspect, the present disclosure provides a technique for sealing or sealing and cutting large vessels/tissue bundles by controlling the power delivered to an end effector from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In accordance with the resent technique, the power delivered to an end effector of a surgical instrument can be varied based on the size of vessels and tissue bundles interacting with the end effector. For conciseness and clarity of disclosure, the techniques for sealing or sealing and cutting large vessels/tissue bundles will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

A technique for controlling the power output from a generator 500 that is delivered to the end effector 125 of a surgical instrument 108 can include an input that represents a state of coagulation of the tissue to allow the energy profile from the generator 500 to be dynamically changed during the tissue treatment process between RF and ultrasonic energy based on the state of coagulation of the tissue being treated by the end effector 125 of the surgical instrument 108 or the size of the vessels or tissue interacting with the end effector 108. This allows the processor 502 to control the generator 500 to switch from RF energy (ENERGY2/RETURN) when a tissue seal is complete to ultrasonic energy (ENERGY1/RETURN) to cut the tissue and complete a procedure. Also, this technique allows the generator 500 to switch to ultrasonic energy at the initial stages of treatment when either the vessel or tissue bundle is too large to seal with RF energy alone. Thus, ultrasonic energy is applied until the size of the vessel or tissue bundle is sufficiently reduced to enable the RF to complete a proper seal. It will be appreciated that the switch between a first form of energy and a second form of energy, and vice versa, can be done by first turning OFF the first form of energy and thereafter turning on the second form of energy. Alternatively, the switch between a first form of energy and a second form of energy, and vice versa, can be done by transitioning from the first form of energy to the second form of energy, and vice versa, such that for brief period both the first and second forms of energy are turned ON simultaneously while one form ramps up and the other ramps down. Thus, according to the latter approach, the RF and ultrasonic energies can be blended during the transition rather than “one then the other” approach.

In one aspect, the present disclosure provides techniques to improve the capability of the generator 500 to quickly and efficiently seal or seal and cut large vessels or large tissue bundles that present an initial extremely low impedance to the generator 500. These techniques shorten transaction times when sealing or sealing and cutting big tissue bundles that present low RF impedance to the generator 500. When RF energy is applied to tissue with real low impedance, due to electrical current capacity limitations (maximum output current capability) of the generator 500, the maximum power that can be delivered into tissue is limited, which results in very long transaction cycles. Note that the current limitation is not unique to the generators described herein and are applicable to other generators.

In one aspect, the state of coagulation of the tissue can be determined using a variety of techniques, In one aspect, the state of coagulation of the tissue is determined using a calculated tissue impedance and comparing it to a threshold to find the termination impedance, as explained above. The calculated tissue impedance, as described herein, is used by a technique to control the energy being delivered from the generator 500 to the surgical instrument 108.

In another aspect, the state of coagulation is determined using a “vector machine” or other techniques. In another aspect, the state of coagulation is determined using neural networks that are configured to take a plurality of factors into account. As discussed herein, a neural network refers to a series of techniques that attempt to identify underlying relationships in a set of data by using a process that mimics the way the human brain operates. Neural networks have the ability to adapt to changing input so that the network produces the best possible result without the need to redesign the output criteria. For example, the neural networks can take into account the tissue impedance as measured using the RF signal, the initial tissue impedance as measured using the RF signal, the energy that went into the transection, for example, in joules, the transection time, the initial aperture of the jaw, the current aperture of the jaw, and/or the rate of change of the tissue impedance. One example of a neural network 5500 for controlling a generator is described hereinbelow in connection with FIG. 82.

FIG. 54 is a logic flow diagram 3300 of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles. As described herein, the logic flow diagram 3300 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3300 shown in FIG. 54 and the surgical system 10 of FIG. 1, the state of coagulation of the tissue is determined as described herein. The generator 500 is configured to deliver RF energy (ENERGY2/RETURN) and ultrasonic energy (ENERGY1/RETURN) to switch between the RF and ultrasonic energy according to various techniques. The end effector 125 of the surgical instrument 108 is advanced and the tissue is clamped 3302 between the clamp arm 145 and the ultrasonic blade 149. The end effector 125 is activated with RF energy from the generator 500 and RF energy is delivered 3304 to the tissue to effect a seal employing a process such as a composite load curve (CLC) control process described in connection with the logic diagram 5400 shown FIG. 81. With reference back to FIG. 54, the processor 502 determines 3306 the state of coagulation to determine if a state of completion of coagulation of the tissue has been achieved, at which time the processor 502 signals the waveform generator 504 and amplifier 506 to switch from RF energy for coagulating tissue to ultrasonic energy for cutting tissue. If the desired tissue of coagulation or seal has not been achieved, the processor 502 continues along the NO branch and RF energy is continued to be delivered. When the proper state of coagulation has been reached, the processor 502 continues along the YES branch and the RF energy is switched 3308 to ultrasonic energy to cut the tissue. The tissue is released 3310 from the end effector 215 once the tissue cut is completed with the ultrasonic energy.

Also disclosed herein are techniques for dynamically changing the energy delivered from a generator based on end effector aperture. According to one aspect, a technique for controlling the power output from a generator, such as the generator 500 of FIG. 8, that is delivered to the end effector of a surgical instrument, such as surgical instrument 108 (FIGS. 1-3) can include an input that represents the aperture of the end effector 125 of the surgical instrument 108. The energy profile from the generator 500 can be dynamically changed during the procedure between RF and ultrasonic energy based on the size of the aperture defined by the end effector 125 clamping the tissue. This allows the generator 500 to switch from RF energy to ultrasonic energy based on the amount that the end effector 125 is clamping on the tissue being treated by the surgical instrument 108. The aperture of the clamp arm 145 is related to the creation of a proper coagulation seal, for example, when RF energy is delivered from the generator 500 to the end effector 125 of the surgical instrument 108, such that RF energy is used when there is sufficient closure of the end effector 125 on the tissue. Thus, if the aperture defined by the end effector is too large and there is insufficient clamp on the tissue for proper coagulation, only ultrasonic energy is delivered to the end effector 125.

For example, false information regarding various tissue measurements and/or characteristics can be transmitted to the generator 500 for controlling the energy delivered depending on the aperture defined by the end effector 125. One such measurement that can be affected by the aperture defined by the end effector 125 is tissue impedance. An incorrect tissue impedance determination can lead to early termination of a coagulation “sealing” cycle as the generator 500 may switch from RF to ultrasonic energy before a proper coagulation seal has been achieved.

The aperture defined by the end effector 125 can be determined using a variety of techniques. In one form, the aperture defined by the end effector 125 is determined by detecting the pivot angle of the end effector 125. This can be accomplished using a potentiometer, a Hall effect sensor, an optical encoder, an optical IR sensor, an inductance sensor, or a combination thereof. In another form, the proximity of first and second components of an end effector 125 is measured to determine the aperture defined by the end effector 125 using, for example, a Hall effect sensor, an optical IR, inductance sensor, or combination thereof. In another form, a surgical instrument 125 is configured to detect the aperture defined by the end effector 125 by measuring a change in a tissue impedance of the tissue interacting with the end effector 125. In another form, a surgical instrument is configured to detect the aperture defined by the end effector 125 by measuring a load applied by the end effector 125 on the tissue as ultrasonic energy is pulsed to the end effector 125. In another form, the surgical instrument includes a switch or other mechanism for closing the end effector 125 that can detect the aperture defined by the end effector 125. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

FIG. 55 is a logic flow diagram 3400 of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles by dynamically changing energy being delivered from the generator 500 during the treatment of the tissue based on the changing aperture defined by the end effector. As described herein, the logic flow diagram 3400 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3400 shown in FIG. 55, the processor 502 determines the aperture defined by the end effector 125 as described above. The processor 502 then determines the state of coagulation of the tissue as described herein. The generator 500 or the surgical instrument 108 may be configured to deliver RF energy (ENERGY2/RETURN) and ultrasonic energy (ENERGY1/RETURN) to switch between the RF and ultrasonic energy according to various techniques. The end effector 125 of the surgical instrument 108 is advanced and the tissue and the end effector 125 of the surgical instrument 108 is closed 3402 on tissue and the end effector 125 is activated with energy from the generator 500. The processor 502 determines 3404 the aperture defined by the end effector 125 using any of the techniques described above. The processor 502 signals the energy delivered from the generator 500 to the end effector 125 and controls when the generator 500 switches between RF and ultrasonic energy based on the aperture defined by the end effector 125. Accordingly, the processor 502 selects 3406 the generator 500 power delivery profile based on the aperture defined by the end effector 125. The processor 502 monitors 3408 the aperture defined by the end effector 125 during the tissue treatment process to dynamically change 3410 the energy delivered from the generator 500 during the tissue treatment process based on the changing aperture defined by the end effector 125.

In another aspect, a technique for controlling the power delivered from the generator 500 to the end effector 125 of the surgical instrument 108 can include an input that includes energy parameters based on an aperture of the end effector 125 of the surgical instrument 108. During the tissue treatment process, the processor 502 can dynamically change the energy output profile of the generator 500 between RF energy and ultrasonic energy using energy parameters based on the aperture defined by the end effector 125 clamping the tissue. This allows the generator 500 to switch from RF energy to ultrasonic energy based on how much clamping force the end effector is applying to the tissue during the treatment process. As explained above, the aperture of the clamp arm 145 is related to creating a proper coagulation seal. For example, RF energy should be delivered by the generator 500 to the end effector 125 only when there is sufficient closure of the end effector 125 on the tissue. Thus, when the aperture defined by the end effector 125 is too large and there is insufficient clamping force on the tissue for proper coagulation, only ultrasonic energy should be delivered to the end effector 125.

The aperture defined by the end effector 125 can be determined using any of the methods described above. For example, the surgical instrument 108 can include an aperture sensor in the end effector 125 that can be fed through a connector to the ASIC in the handle 109 of the surgical instrument 108. The surgical instrument 108 also can include a sensor in the handle 109 of the surgical instrument 108 that is configured to detect the aperture defined by the end effector 125.

Energy parameters are configured to be loaded into the generator 500, and can include a plurality of different parameters, including but not limited to voltage, current, power, and one or more techniques for use in treating tissue. These parameters can be related to the RF energy and ultrasonic energy that can be delivered from the generator 500. The energy parameters can include information such as maximum and/or minimum values to be used to control the energy delivered from the generator 500. The energy parameters can be stored in a variety of locations, including an EEPROM on the surgical instrument 108 or some other non-volatile memory. In addition, there can be multiple sets of energy parameters. For example, the processor 502 can use a first set of energy parameters to optimize tissue transection, and a second set of energy parameters to optimize tissue spot coagulation. It will be understood that there can be any number of set of energy parameters that correspond to various types of tissue treatments to allow the generator 500 to switch between the various sets of energy parameters based on the necessary tissue treatments.

When the end effector 125 of the surgical instrument 108 is activated, the processor 502 utilizes the various techniques described above to detect the aperture defined by the end effector 125. In one aspect, when the end effector 125 is closed around the tissue, the generator 500 can utilize the energy parameters for optimizing tissue transection. When the end effector 125 has a larger aperture and is not clamped on the tissue, the generator 500 can utilize the energy parameters for optimizing spot coagulation of the tissue.

FIG. 56 is a logic flow diagram 3500 of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles by dynamically communicating energy parameters to the generator 500 during the tissue treatment process based on the changing aperture defined by the end effector 125 of the surgical instrument 108. As described herein, the logic flow diagram 3500 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram 3500 shown in FIG. 56, the processor 502 determines the aperture defined by the end effector 125 as described above. The generator 500 is configured to deliver RF energy (ENERGY2/RETURN) and ultrasonic energy (ENERGY1/RETURN) and to switch between the RF and ultrasonic energy according to various techniques. The end effector 125 of the surgical instrument 108 is advanced, the end effector 125 of the surgical instrument 108 is closed 3502 on the tissue. and the end effector 125 is activated with energy from the generator 500. The processor 502 determines 3504 the aperture defined by the end effector 125 using any of the techniques described above. The processor 502 signals the energy delivered from the generator 500 and to switch between RF and ultrasonic energy based on the aperture defined by the end effector 125 based on sets of energy parameters previously loaded into the generator 500. Accordingly, energy parameters are communicated 3506 to the generator 500 based on the measured aperture defined by the end effector 125. The aperture defined by the end effector 125 is monitored 3508 during the tissue treatment process such that the energy delivered from the generator 500 can be dynamically changed during the tissue treatment process based on the changing aperture defined by the end effector 125. Accordingly, the processor 502 dynamically communicates 3510 energy parameters to the generator 500 based on the measured aperture defined by the end effector 125. This allows the generator 500 to dynamically switch between various sets of energy parameters based on the changing aperture defined by the end effector 125.

It will be understood that various combinations of information can be used to determine which set of energy parameters are to be used during the tissue treatment process. For example, the aperture defined by the end effector 125 and calculated tissue impedance can be used by the processor 502 to determine which set of energy parameters are needed to control the energy being delivered from the generator 500. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

In another aspect, a technique for controlling the power output from the generator 500 and delivered to the end effector 125 of the surgical instrument 108 can include an input that includes inputs related to the size of the tissue being treated by the end effector 125 of the surgical instrument 108. During the tissue treatment process, the processor 502 dynamically changes the energy delivered from the generator 500 between RF energy and ultrasonic energy to achieve dissection and coagulation of large vessels and large tissue bundles based on a determination of the effectiveness of the RF energy in coagulating the large vessels or large tissue bundles. A determination of the effectiveness of the RF energy in coagulating a tissue includes a calculation of tissue impedance, as explained above, of the large tissue interacting with the end effector 125, which is used to determine the type of energy delivered by the generator 500 to the end effector 125.

FIG. 57 is a logic flow diagram 3600 of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements and the aperture defined by the clamp arm measurements. As described herein, the logic flow diagram 3600 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3600 shown in FIG. 57, the end effector 125 is advanced and the clamp arm 145 is closed 3602 on tissue located between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125. The end effector 125 is then activated with RF energy (ENERGY2/RETURN) from the generator 500 to form a seal. The processor 502 determines 3604 the tissue impedance and the aperture defined by the end effector 125 as described herein. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

The aperture defined by the end effector 125 and the processor 502 determines 3604 the tissue impedance using any of the techniques described herein. The processor 502 compares 3606 the tissue impedance values to stored threshold values and determines 3608 whether or not these values are greater than the threshold values. If either the tissue impedance or the aperture defined by the end effector 125 is less than the threshold value, the processor 502 continuous along the NO branch and RF energy (ENERGY2/RETURN) continues to be delivered from the generator 500 to the end effector 125. If the tissue impedance and the aperture defined by the end effector 125 are greater than the threshold value, the processor 502 continues along the YES branch and switches 3610 the to delivering ultrasonic energy (ENERGY1/RETURN) from the generator 500. This allows the large vessels and large tissue bundles to be reduced in size or shrunk with ultrasonic energy to a size that would allow the RF energy to form a more optimal seal.

The processor 502 determines 3612 the aperture defined by the end effector 125 using any of the techniques described herein. The processor 502 then compares 3614 these aperture values to stored threshold aperture values and determines whether or not these aperture values represent that the tissue has been shrunk by the ultrasonic energy to a size that would allow the RF energy to properly seal the tissue. If the processor 502 determines that tissue is too large for RF energy sealing, the processor 502 continues along the NO branch and ultrasonic energy continues to be delivered from the generator 500 to the end effector 125 to continue shrinking the tissue. If the processor 502 determines that the tissue is has been shrunk to an appropriate size suitable for sealing with RF energy, the processor 502 continues along the YES branch and switches 3616 the energy delivered from the generator 500 to RF energy. The processor 502 signals can optionally switch back 3618 to delivering ultrasonic energy upon determining that the RF energy has completed the tissue seal.

FIG. 58 is a logic flow diagram 3700 of one aspect of a process for sealing or sealing and cutting large vessels or large tissue bundles. As described herein, the logic flow diagram 3700 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3700 shown in FIG. 58, tissue is initially grasped 3702 by the end effector 125 between the clamp arm 145 and the ultrasonic blade 149. RF energy (ENERGY2/RETURN) is delivered 3704 to the end effector 125. The processor 502 monitors 3706 the tissue impedance Z_(T) and jaw aperture A_(j) for a predetermined period T_(o), which may be selected from a range of 0.5 to 2.0 seconds, and preferably about 1.5 seconds, for example. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

Until the predetermined period T_(o) elapses 3708, the processor 502 continues along the NO branch and the generator 500 continues to deliver RF energy and the processor 502 continues to monitor (measure) tissue impedance Z_(T) and jaw aperture A_(j). At the end of the time period T_(o), if tissue impedance Z_(T) has not increased to a value equal to or greater than a predetermined threshold and the jaw aperture is equal to or less than a predetermined threshold, the processor 502 proceeds along the YES branch and switches 3710 the generator 500 to ultrasonic energy mode. Ultrasonic energy is delivered 3712 to the tissue while the processor 502 monitors the tissue impedance Z_(T) and jaw aperture A_(j) until the tissue shrinks to a size that is suitable for sealing with RF energy. The processor 502 compares 3714 the jaw aperture A_(j) to a threshold jaw aperture and if it is less than or equal to the threshold the processor 502 continues along the YES branch assuming that the tissue is sized for sealing by RF energy. The processor 502 switches the generator 500 to RF energy mode and delivers 3716 RF energy to complete the seal while the processor 502 monitors the tissue impedance Z_(T) to determine 3718 if the seal is complete. If the seal is complete and seal-only is desired, the processor 502 completes 3720 the operation. If the seal is complete and seal and cut is desired, the processor 502 switches the generator 500 to ultrasonic energy mode and delivers 3722 ultrasonic energy to cut the sealed tissue. Upon cutting the tissue, the processor 502 completes 3720 the operation.

FIG. 59 is a logic flow diagram 3800 of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements. As described herein, the logic flow diagram 3800 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3800 shown in FIG. 59, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. The processor 502 signals the waveform generator 504 and amplifier 506 to deliver 3802 RF energy (ENERGY2/RETURN) to the end effector 125 of the surgical instrument 108 interacting with tissue to create a tissue seal using the RF energy. The processor 502 calculates 3804 a first tissue impedance Z_(T1) of the tissue interacting with the end effector 125 at the start of the period T_(o) of the delivery of the RF energy and then calculates 3806 a second tissue impedance Z_(T2) of the tissue interacting with the end effector after the RF energy is delivered for a predetermined period T₁. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

The processor 502 compares Z_(T1) to Z_(T2). If Z_(T2) is less than or equal to Z_(T1), after RF energy is delivered for a period of T₁, there may be a short circuit or the tissue impedance is too low for RF energy to deliver power to the tissue. Accordingly, the processor 502 proceeds along the YES branch and controls the waveform generator 504 and amplifier 506 to stop 3810 delivering RF energy to the end effector 125 and start delivering 3812 ultrasonic energy to the end effector 125 until Z_(T2) is greater than Z_(T1). Once Z_(T2) exceeds Z_(T1), the processor 502 continues along the NO branch and controls the waveform generator 504 and amplifier 506 to continue 3814 delivering RF energy to the end effector 125 until the tissue is sealed 3816. Once the tissue is sealed, the processor 502 continues along the YES branch and the controls the waveform generator 504 and amplifier 506 to stop delivering RF energy to the end effector 125 and to start delivering 3820 ultrasonic energy to cut the tissue. If the tissue is not sealed, the processor 502 continues along the NO branch and the generator 500 continues delivering RF energy to the end effector until the tissue seal is completed.

In another aspect, a technique for controlling the power output from the generator 500 delivered to the end effector 125 of the surgical instrument 108 can include an input that includes inputs related to the size of the tissue being treated by the end effector 125 of the surgical instrument 108. The energy delivered from the generator 500 can be dynamically changed during the procedure between RF and ultrasonic energy to achieve dissection and coagulation of a large tissue based on a determination of the effectiveness of the RF energy in coagulating the large tissue. A determination of the effectiveness of the RF energy in coagulating a tissue includes a calculation of tissue impedance, as explained above, of the large tissue interacting with the end effector 125, which is used to determine the type of energy being delivered by the generator 500 to the end effector 125.

FIG. 60 is a logic flow diagram 3900 of a technique to seal or seal and cut vessels using RF and ultrasonic energy in conjunction with tissue impedance measurements and the aperture defined by the clamp jaw measurements. As described herein, the logic flow diagram 3900 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 3900 shown in FIG. 60, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. The processor 502 signals the waveform generator 504 and amplifier 506 to deliver 3902 RF energy (ENERGY2/RETURN) to the end effector 125 of the surgical instrument 108 interacting with tissue to create a tissue seal using the RF energy. The processor 502 calculates 3904 a first tissue impedance Z_(T1) of the tissue interacting with the end effector 125 at the start of a period T_(o) of delivery of the RF energy and then calculates 3906 a second tissue impedance Z_(T2) of the tissue interacting with the end effector 125 after the RF energy is delivered for a predetermined period T₁ and measures the aperture A_(j) defined by the clamp arm 145. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

The processor 502 compares Z_(T1) to Z_(T2). If Z_(T2) is less than or equal to Z_(T1) after RF energy is delivered for a period of T₁, the processor 502 determines that there may be a short circuit or extremely low the tissue impedance present at the end effector 125 that is too low for RF energy to deliver any power to the tissue. Accordingly, the processor 502 proceeds along the YES branch and the generator 500 and compares the measured aperture A_(j) defined by the clamp arm 145 to a predetermined threshold aperture A_(jo) defined by the clamp arm 145, where the predetermined threshold aperture A_(jo) d corresponds to a thick vessel or a thick tissue bundle located between the clamp arm 145 and the ultrasonic blade 149. If the measured aperture A_(j) defined by the clamp arm 145 is less than or equal to the predetermined threshold aperture A_(jo), the processor 502 continues along the NO branch and controls the waveform generator 504 and amplifier 506 to continue delivering RF energy to the end effector 125 until the tissue impedance Z_(T2) is less than the initial tissue impedance Z_(T1). If the measured aperture A_(j) defined by the clamp arm 145 is greater than the predetermined threshold aperture A_(jo), the processor 502 continues along the YES branch and controls the generator to stop 3110 delivering RF energy to the end effector 125 and start delivering 3112 ultrasonic energy (ENERGY1/RETURN) to the end effector 125 until Z_(T2) is greater than Z_(T1). Once Z_(T2) is greater than Z_(T1) the processor 502 continues along the NO branch and controls the waveform generator 504 and amplifier 506 to continue 3114 delivering RF energy to the end effector 125 until the tissue is sealed 3116. Once the tissue is sealed, the processor 502 continues along the YES branch and controls the waveform generator 504 and amplifier 506 to stop delivering RF energy and start delivering 3920 ultrasonic energy to the end effector 125 to cut the tissue. If the tissue is not sealed, the processor 502 continues along the NO branch and controls the waveform generator 504 and amplifier 506 to continue delivering RF energy to the end effector 125 until the tissue seal is complete.

Techniques for Switching Between RF and Ultrasonic Energy Based on the State of Coagulation of Tissue

In one aspect, the present disclosure provides a technique for switching between RF and ultrasonic energy based on the state of coagulation of tissue by controlling the power delivered to an end effector from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In accordance with the present technique, the power delivered to an end effector of a surgical instrument can be switched between RF and ultrasonic based on the state of coagulation of tissue interacting with the end effector. For conciseness and clarity of disclosure, the techniques for switching between RF and ultrasonic energy based on the state of coagulation of tissue will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

To address these issues, in some aspects, a generator 500 capable of handling both ultrasonic and RF electrosurgical systems may include a completely nested neural network to identify whether the generator 500 is presented with a true short circuit vs. a low impedance tissue. In addition, in some aspects, to assist in the detection of short circuits, the neural network may be configured to track and store at least the following factors: a. Measured resistance/impedance; b. Drive current (RMS); c. Drive Voltage (RMS); and d. Moving average of measured impedance. In some aspects, the neural network will be thought to in order to be capable of discerning between a true short and low impedance tissue.

Furthermore, in some aspects, methods for detecting a short circuit may utilize the ultrasonic functionality to cut low impedance tissue and to identify a true short circuit. For example, instead of faulting, the generator 500 may send in an exploratory pulse to the ultrasonic transducer 120. The tissue properties initially assessed by the ultrasonic blade 149 touching a metal short would result in a higher output drive voltage and resulting impedance. This level of impedance may be measured to determine whether the material was actually metal versus low impedance tissue. If the processor 502 determines that metal is not present in the end effector 125, the generator 500 continues to deliver ultrasonic energy to the end effector 125 and cut through the load. Thus, if the impedance is too low for the application of RF energy to seal the tissue in a timely manner, ultrasonic energy could be applied cut through non-metal low impedances without difficulty.

FIG. 61 is a logic flow diagram 4000 of one aspect of a technique for distinguishing a short circuit from low impedance tissue while utilizing RF energy by measuring voltage properties of an exploratory ultrasonic pulse. As described herein, the logic flow diagram 4000 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to FIG. 61, the logic flow diagram 4000 provides a method for distinguishing a short circuit from low impedance tissue. With reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the processor 502 signals the waveform generator 504 and amplifier 506 to transition 4002 from delivering RF energy (ENERGY2/RETURN) to delivering ultrasonic energy (ENERGY1/RETURN). The processor 502 then controls the waveform generator 504 and amplifier 506 to transmit 4004 an exploratory pulse to the ultrasonic transducer 120 to apply ultrasonic energy to the short circuit area in question. The processor 502 then measures 4006 the output drive voltage and drive current and determines the impedance. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514. At this juncture, the processor 502 determines 4008 whether the impedance is consistent with low impedance tissue. When the impedance is consistent with low impedance tissue, the processor 502 proceeds along the YES branch and controls the waveform generator 504 and amplifier 506 to continue 4010 delivering ultrasonic energy to cut through tissue. When the impedance is not consistent with low impedance tissue, the processor 502 proceeds along the NO branch and controls the waveform generator 504 and amplifier 506 to stop 4012 the application of ultrasonic energy.

Additionally, in some aspects, if a short is detected while in RF mode and delivering RF energy to the end effector 125, the processor 502 signals the waveform generator 504 and amplifier 506 to transmit an ultrasonic pulse to the ultrasonic transducer 120. A microphone and ultrasonic application can be configured to detect the sound of characteristic ultrasonic vibrations against metal, since it would be very apparent and instantly or easily recognizable. Using knowledge in acoustics and waveform engineering, the processor 502 can account for what frequencies are heard due to the ultrasonic blade 149 acting on metal and on other non-tissue materials.

FIG. 62 is a logic flow diagram 4100 of a technique for distinguishing a short circuit from low impedance tissue while delivering RF energy and measuring acoustic properties of an exploratory ultrasonic pulse, according to some aspects. As described herein, the logic flow diagram 4100 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to FIG. 62, the logic flow diagram 4100 provides a method for distinguishing a short circuit from low impedance tissue. The tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the processor 502 signals the waveform generator 504 and amplifier 506 to transition 4102 from delivering RF energy (ENERGY2/RETURN) to delivering ultrasonic energy (ENERGY1/RETURN). The processor 502 then controls the waveform generator 504 and amplifier 506 to transmit 4104 an exploratory pulse to the ultrasonic transducer 120 to apply ultrasonic energy to the short circuit area in question. The processor 502 measures 4106 the acoustic properties of the area in question based on applied ultrasonic vibrations. At this juncture, the processor 502 determines 4108 whether the acoustic properties are consistent with the low impedance tissue. When the processor 502 determines acoustic properties are consistent with low impedance tissue, the processor 502 proceeds along the YES branch and controls the waveform generator 504 and amplifier 506 to continue 3210 delivering ultrasonic energy to cut through tissue. When the processor 502 determines that the acoustic properties are consistent with low impedance tissue, the processor 502 proceeds along the NO branch and controls the waveform generator 504 and amplifier 506 to stop 4112 delivering ultrasonic energy.

In some aspects, a neural network, such as neural network 5500 for controlling a generator shown in FIG. 82, may be programmed to identify these properties in metal, tissues, and other non-tissue materials. The neural network also may be configured to transmit the exploratory pulse to the ultrasonic transducer. In addition, new developments or additional programs, including receiving feedback from the attempts to detect short circuits, may be incorporated back into the neural network to increase its situational awareness and effectively better learn how to detect a true short circuit. Wth confirmation of a short circuit both by RF and ultrasonic functionality, this can allow for less time spent getting repeat errors on RF and faster transection on low impedance tissue.

Also disclosed herein are techniques for combining RF energy and ultrasonic energy to seal tissue without cutting. In some aspects, the surgical system including the generator of the present disclosures may be configured to implement a method for sealing tissue at a surgical site without cutting, by using a combination of ultrasonic energy and RF energy. In some aspects, the method includes superimposing the ultrasonic drive signal together with a fixed low RF signal (e.g., ultrasonic at 55.5 KHz and RF at 330 KHz). For example, during a sealing procedure, the ultrasonic drive signal may be configured to dynamically change in order to: (1) track the resonance of the ultrasonic drive signal, and (2) provide the desired strength or amplitude of vibrations in order to achieve the desired tissue effect. The fixed low RF signal will be provided in order to measure the tissue impedance and modify the ultrasonic drive to achieve the desired seal without cutting.

The RF signal may be superimposed in several non-exhaustive ways. In one way, the RF drive signal may be superimpose on top of the ultrasonic drive signal in a continuous fashion. In another way, the ultrasonic drive signal may be time sliced in such way that periodically or aperiodically, e.g., every 250 mSec, the ultrasonic drive signal will cease and a short burst of the RF drive signal of, e.g., 50 mSec, will be driving the output at a sub-therapeutic level which will still be sufficient to measure tissue impedance. After this burst, the processor 502 will control the waveform generator 504 and the amplifier 506 to switch the output of the generator 500 back to delivering the ultrasonic drive signal. The overall control loop may be configured to monitor the RF tissue impedance and adjust the ultrasonic drive signal output to achieve a tissue seal without cutting the tissue.

FIG. 63 is a logic flow diagram 4200 of a technique for conducting a tissue sealing technique without cutting by using a combination of ultrasonic energy and RF energy, according to some aspects. As described herein, the logic flow diagram 4200 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to FIG. 63, the logic flow diagram 4200 provides an example iterative technique for cyclically combining RF energy (ENERGY2/RETURN) and ultrasonic energy (ENERGY1/RETURN) to seal tissue without cutting, according to some aspects. Tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the processor 502 signals the waveform generator 504 to deliver 4202 an ultrasonic drive signal during a first interval of time to seal tissue at a surgical site. The processor 502 then controls the waveform generator 504 and the amplifier 506 to cease 4204 the ultrasonic drive signal after the first interval. The processor 502 then controls the waveform generator 504 and the amplifier 506 to deliver an RF drive signal at a sub-therapeutic amplitude during a second interval of time to measure tissue impedance. The processor 502 then controls the waveform generator 504 and the amplifier 506 to cease 4208 the RF drive signal after the second interval of time. The processor 502 then adjusts 4210 an ultrasonic drive signal based on the measured impedance from the RF drive signal. The processor 502 repeats 4212 the procedure until the surgical site is sealed.

The input to this control system to reduce/modify the ultrasonic drive signal and at eventually completely terminate the ultrasonic drive signal can utilize the following non-exhaustive methods: follow a power reduction and termination technique based on regular logic, fuzzy logic, vector machine, or neural network utilizing the following example: initial tissue impedance, initial jaws-aperture, current tissue impedance, rate of change of tissue impedance, energy driven into tissue, and transection time.

In some aspects, the surgical system may be configured to measure these terms through one or more sensors. Example methods for monitoring these terms and the ultrasonic functionality of the combination RF and ultrasonic surgical system may be based on methods described in U.S. Pat. No. 9,017,326, titled “Impedance Monitoring Apparatus, System, And Method For Ultrasonic Surgical Instruments,” which is hereby incorporated by reference in its entirety.

FIG. 64 is a logic flow diagram 4300 of a technique for conducting a tissue sealing technique without cutting by using a combination of ultrasonic energy and RF energy, according to some aspects. As described herein, the logic flow diagram 4300 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to FIG. 64, the logic flow diagram 4300 provides an example iterative technique for cyclically combining RF energy (ENERGY2/RETURN) and ultrasonic energy (ENERGY1/RETURN) to seal tissue without cutting, according to some aspects. Tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the processor 502 signals the waveform generator 504 to deliver 4302 an ultrasonic drive signal to the tissue during a first interval of time T₁. The processor 502 then controls the waveform generator 504 and the amplifier 506 to cease 4304 the ultrasonic drive signal after the first interval T₁. The processor 502 then controls the waveform generator 504 and the amplifier 506 to deliver 4306 an RF drive signal at a sub-therapeutic amplitude during a second interval T₁ of time to measure the tissue impedance. The processor 502 then controls the waveform generator 504 and the amplifier 506 to cease 4308 the RF drive signal after the second time interval T₂. The processor 502 then controls the waveform generator 504 and the amplifier 506 to iteratively adjust 4310 the ultrasonic drive signal based on the measured tissue impedance until the processor 502 determines that the tissue is sealed. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

Techniques for Improving Short Circuit Detection in a Combination Ultrasonic/RF Surgical Instrument

In one aspect, the present disclosure provides a technique for detecting extremely low impedances or actual short circuits in the end effector by controlling the power delivered to an end effector from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In accordance with the present technique, the power delivered to an end effector of a surgical instrument can be varied based on whether a very low impedance or actual short circuit condition is present at the end effector. For conciseness and clarity of disclosure, the techniques for detecting extremely low impedances or actual short circuits in the end effector will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

Disclosed herein are techniques for detecting short circuits, including implementing detection methods in a neural network. In some aspects, the ultrasonic generator 500 of the present disclosures includes components configured to accurately and reliably detect short circuits. Particularly when performing surgeries on body tissue typical with use of the end effectors described herein, detecting a short circuit can be difficult for a number of reasons. For example, many times tissue presents itself as a short circuit, thereby fooling the detection software and at low signal magnitudes, which are inherent when driving signals with a short circuit, the measurement(s) error(s) is/are substantial and can result in making the wrong decision whether the generator is presented with a true short circuit. In addition, in some aspects of the generator described herein, low impedance tissue or metal shorts cause the generator to fault while in RF mode. In general, it may be difficult for the generator to distinguish between low impedance tissue and metal, where one may result in a true short circuit while the other is merely based on low impedance tissue.

FIG. 65 is logic flow diagram 4400 of a technique for detecting low impedance tissue or metal shorts that may cause false short circuits in RF mode. As described herein, the logic flow diagram 4400 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to FIG. 65, the logic flow diagram 4400 provides an example technique for detecting low impedance tissue or metal shorts that may cause false short circuits in RF mode. Tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, if the processor 502 cannot distinguish low impedance tissue from metal located between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125, the processor 502 signals the waveform generator 504 to deliver ultrasonic energy (ENERGY1/RETURN) to cut low impedance tissue and to identify a true short circuit, such as metal to metal contact between the clamp arm 145 and the ultrasonic blade 149. In accordance with the method, the processor 502 signals the waveform generator 504 to deliver 4402 RF energy (ENERGY2/RETURN) with the end effector 125 to the target surgical site. The processor 502 then controls the waveform generator 504 and the amplifier 506 to transition 4404 from delivering RF energy to delivering ultrasonic energy to the end effector 125. The processor 502 signals the waveform generator 504 to transmit 4406 an exploratory ultrasonic pulse to the end effector 125 and then measures 4408 an ultrasonic property of the ultrasonic pulse upon transmission to the end effector 125.

Techniques for Delivering Pulsed RF and Ultrasonic Energy in a Combination Ultrasonic/RF Surgical Instrument

In one aspect, the present disclosure provides a technique for delivering RF and ultrasonic energy to an end effector of a surgical instrument by controlling the power delivered to an end effector from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In accordance with the present technique, the power delivered to an end effector of a surgical instrument can be varied based on properties or parameters of tissue interacting with the end effector. For conciseness and clarity of disclosure, the techniques for delivering RF and ultrasonic energy to the end effector will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

FIGS. 66-75 illustrate aspects of timing diagrams of energy pulses for delivering different energy modalities to tissue. In one aspect the first energy modality is RF energy and the second energy modality is ultrasonic energy. There are many benefits to a surgical device that is capable of delivering both RF and ultrasonic energy. A surgical instrument capable of delivering both modalities provides stronger seals and can cut tissue without the need of a separate knife. The following disclosure provides multiple pulsing techniques than can be utilized for vessel sealing. These techniques employ tissue impedance measurements, current measurements, can seal only, and can seal and cut tissue. These techniques may be implemented using multiple generators, one generator configured to deliver RF energy and another generator configured to deliver ultrasonic energy. Alternatively, these techniques may be implemented with a single generator configured to deliver both RF and ultrasonic energy. In other aspects, these techniques may be implemented with a single generator that is configured to deliver RF and ultrasonic energy simultaneously through a single output port.

These techniques comprise pulsing between RF and ultrasonic energy modalities to create strong seals. Multiple configurations of pulsing are disclosed. The pulse sequence timing diagrams illustrated in FIGS. 57-63 and the logic flow diagrams shown in FIGS. 64-66 will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8. Tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the generator 500 delivers the pulse sequences discussed below.

FIG. 66 is a timing diagram of a seal only pulse sequence 4500 illustrating a basic configuration of pulsing RF and ultrasonic energy for “Seal Only” mode. The horizontal axis is time (t) in seconds that the energy is delivered or “pulsed.” The vertical axis is the current pulse amplitude in milliamps (mA) that the pulse is capable of sourcing. The ultrasonic energy pulses 4502 are shown in dashed line and the RF pulses 4504 are shown in solid line. As shown in FIG. 66, the generator 500 switches between the ultrasonic energy pulses 4502 and RF energy pulses 4504 at fixed time intervals. During a first half cycle, the pulse sequence starts with the RF energy pulse 4504 ON for about 1 mS at a current pulse of about 750 mA amplitude while the ultrasonic energy pulse 4502 is OFF for about 1 mS at 0 mA current amplitude. During the next half cycle, the RF energy pulse 4504 is OFF for about 1 mS at 0 mA current amplitude while ultrasonic energy pulse 4502 is ON for about 1 ms at a current pulse of about 350 mA amplitude. The cycle is repeated until a strong tissue seal is developed. It will be appreciated that the application of the sequence of ultrasonic energy pulses 4502 and RF energy pulses 4504 shown in the pulse sequence 4500 is suitable for effecting a tissue seal only. This configuration of pulse sequence can start either with an RF energy pulse 4504 or an ultrasonic energy pulse 4502. Ultimately energy delivery for a “Seal Only” mode would be stopped based on the tissue impedance measured on the RF pulses 4504.

In order to reduce the risk of cutting tissue with the ultrasonic energy pulses 4502, the number of ultrasonic energy pulses 4502 should be minimized. This configuration is shown in FIG. 67, which is a timing diagram of a seal only pulse sequence 4510 illustrating a basic configuration of pulsing RF and ultrasonic energy for “Seal Only” mode. As shown, the pulse sequence 4500 starts with an active RF energy pulse 4504. After two ultrasonic energy pulses 4502, or other predetermined limited number of ultrasonic energy pulses 4502, no more ultrasonic energy pulses 4502 are delivered after the last ultrasonic energy pulse 4502′ and the RF energy pulse 4504′ is delivered for an extended period to effect a seal only. To avoid cutting the tissue with the ultrasonic energy pulse 4504 the last RF energy pulse 4504′ remains ON at high amplitude while the ultrasonic energy pulse 4502 remains OFF.

It can be appreciated that the seal on the clamp arm 145 side may be wider and more complete than a seal on the ultrasonic blade 149 side. This may be caused by insufficient heating on the ultrasonic blade 149 side due to the higher thermal mass of the ultrasonic blade 149. In order to address this issue, the ultrasonic energy pulse 4502 could be left ON longer at the beginning to get the ultrasonic blade 149 up to the sealing temperature. FIG. 68 is a timing diagram of a seal only pulse sequence 4520 illustrating a basic configuration of pulsing RF and ultrasonic energy to preheat the ultrasonic blade 149. FIG. 68 is a timing diagram of a seal only pulse sequence 4520. As shown in FIG. 68, the first energy pulse delivered is an ultrasonic energy pulse 4502, which is left ON for an extended period sufficient to preheat the ultrasonic blade 149 prior to applying the RF energy pulses 4504. To avoid cutting the tissue with the ultrasonic energy pulse 4504 the last RF energy pulse 4504′ remains ON at high amplitude while the ultrasonic energy pulse 4502 remains OFF.

FIG. 69 is a timing diagram of a seal only pulse sequence 4530. One of the main benefits to having more than one pulse of ultrasonic energy 4502 is to maintain the ultrasonic blade 149 temperature. In order to maintain ultrasonic blade 149 temperature and reduce the risk of cutting tissue with the ultrasonic blade 149, the pulse sequence 4530 shown in FIG. 69 provides the first ultrasonic energy pulse 4502 at a high amplitude and then the subsequent ultrasonic energy pulses 4502′, 4502″ at lower amplitudes. To avoid cutting the tissue with the ultrasonic energy pulse 4504 the last RF energy pulse 4504′ remains ON at high amplitude while the ultrasonic energy pulse 4502 remains OFF.

The conditions for switching between the RF energy pulse 4504 and the ultrasonic energy pulse 4502 could be based on a fixed time or it could be based on tissue impedance. For example, when a “Seal Only” mode is desired, as shown in FIGS. 57-60, if a certain Impedance threshold is reached, the technique would not switch over to ultrasonic energy to minimize the risk of cutting through the tissue. The frequency slope could also be used as a trigger to switch from ultrasonic energy pulse 4502 delivery to RF energy pulse 4504 delivery.

If a “Seal and Cut” energy modality is desired, an ultrasonic energy pulse 4502 step could be added to the end of any of the techniques described in connection with FIGS. 57-60. This could occur once a certain impedance threshold is met. FIGS. 61 and 62 illustrate timing diagrams for seal and cut pulse sequences 4540, 4550 for issue seal and cut modes.

FIG. 70 is a timing diagram of a seal and cut pulse sequence 4540, which begins and ends with ultrasonic energy pulses 4502 delivered at the same amplitude during the sealing a cutting cycles. A first ultrasonic energy pulse 4502 is delivered at a predetermined amplitude and subsequent ultrasonic energy pulses 4502 are delivered at the same predetermined amplitude. The RF energy pulses 4504 are delivered until the tissue is sealed or until the tissue impedance is equal to or greater than a predetermined threshold. After the last delivered RF energy pulse 4504′ is turned OFF, the last ultrasonic energy pulse 4502′ is turned ON to cut tissue.

FIG. 71 is a timing diagram of a seal and cut pulse sequence 4550, which begins and ends with ultrasonic energy pulses 4502 delivered at variable amplitude during the sealing a cutting cycles. A first ultrasonic energy pulse 4502 is delivered at a predetermined amplitude and subsequent ultrasonic energy pulses 4502 are delivered at different amplitudes, and in one example as a stepped down amplitude. As shown, for example, a second ultrasonic energy pulse 4502′ is delivered at an amplitude lower than the first amplitude and a third ultrasonic energy pulse 4502″ is delivered at an amplitude that is lower the second predetermined amplitude. The RF energy pulses 4504 are delivered until the tissue is sealed or until the tissue impedance is equal to or greater than a predetermined threshold. After the last delivered RF energy pulse 4504′ is turned OFF, the last ultrasonic energy pulse 4502′″ is turned ON to cut tissue. The last ultrasonic energy pulse 4502′″ may be delivered at an amplitude that either the same as the first amplitude, may be different than previous amplitudes, or may be equal to one of the intermittent amplitudes.

For the seal and cut pulse sequences 4540, 4550, on thick tissue applications, the ultrasonic modality take approximately 250 ms to seek, meaning that low pulse widths result in a short amount of therapeutic time. In some aspects, pulse widths longer than 500 ms, for example, may provide certain benefits.

FIG. 72 is a timing diagram of a seal only pulse sequence 4560 where the ultrasonic energy pulse 4502 current is be set based on the impedance measured with the preceding RF energy pulse 4504. The right vertical axis is tissue impedance in Ohms. The ultrasonic energy pulse 4502 current could be set based on the impedance measured with the preceding RF energy pulse 4504. It would be preferred to have the ultrasonic energy pulse 4502 current high when the preceding RF impedance was low. As the RF impedance increases the ultrasonic energy pulse 4502 current of the next pulse would decrease. This would allow the technique to compensate for the amount of tissue positioned within the jaws of the end effector 125, where thick tissue/bundle applications would stay at lower impedance for a longer period of time and would require more energy/heat to seal. As shown in FIG. 72, based on the first two low tissue impedance 4506 measurements the ultrasonic energy pulse 4502 current amplitude remains the same. After the third tissue impedance 4506′ measurement, the amplitude of the ultrasonic energy pulse 4502′ current is reduced until the tissue impedance exceeds a predetermined threshold and the RF energy pulse 4504′ current remains ON while the ultrasonic energy pulse 4502 current amplitude remains at 0 mA.

In one aspect the first energy modality is RF energy and the second energy modality is ultrasonic energy. In one aspect, the process depicted by the logic flow diagram 4600 may be repeated until the tissue is sealed. As discussed in connection with FIGS. 57-60, in a seal only method, the ultrasonic energy modality may be turned off after a few predetermined number of cycles or based on tissue impedance measurements to avoid cutting the tissue while the RF energy modality is delivered to make a tissue seal. The ultrasonic and/or the RF energy modalities may be delivered at the same amplitude or at variable amplitudes. For example, the RF energy modality may be delivered at the same amplitude whereas the amplitude of the ultrasonic energy modality is stepped down. As discussed in connection with FIGS. 61 and 62, during a seal and cut cycle, the ultrasonic energy modality is delivered last to effect a tissue after the tissue is sealed. As previously discussed, during the sealing cycle, the amplitude of the ultrasonic energy modality may be the same or may be stepped down. A discussed in connection with FIG. 72, in a seal only method, the amplitude of the ultrasonic energy modality is adjusted base don the previous tissue impedance measurement utilizing the RF energy modality. In any of the seal or seal and cut methods discussed above, the ultrasonic energy may be delivered first to preheat he ultrasonic blade 149 because of the higher thermal mass of the ultrasonic blade 149 with respect to the thermal mass of the clamp arm 145.

FIG. 73 is a logic flow diagram 4600 of a technique for delivering pulses of different energy modalities to tissue. As described herein, the logic flow diagram 4600 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 4600 of FIG. 73, initially, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the processor 502 signals the waveform generator 504 to deliver the pulse sequences discussed below. In accordance with the method, the processor 502 activates 4602 a first energy modality of the surgical instrument 108. After a first period, the processor 502 deactivates 4604 the first energy modality and activates 4606 a second energy modality for a second period. The second energy modality is activated 4606 independent of the first energy modality. After the second period expires, the processor 502 deactivates 4608 the second energy modality.

FIG. 74 is a logic flow diagram 4700 of a technique for delivering pulses of different energy modalities to tissue. As described herein, the logic flow diagram 4700 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 4700 of FIG. 74, initially, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the processor 502 signals the waveform generator 504 to deliver the pulse sequences discussed herein. In accordance with the method, the processor 502 activates 4702 an RF energy modality of the surgical instrument 108 to drive RF energy through electrodes located in the clamp arm 145 of the end effector 125. The processor 502 deactivates 4704 the RF energy modality upon detecting a first predetermined tissue impedance Z_(T1) measured at the end effector 125 of the surgical instrument 108. The generator 500 then activates 4706 an ultrasonic energy modality of the surgical instrument 108 to drive the ultrasonic blade 149. The processor 502 deactivates 4708 the ultrasonic energy modality upon detecting a second predetermined tissue impedance Z_(T2) at the end effector 125 of the surgical instrument 108. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

FIG. 75 is a logic flow diagram 4000 of a technique for delivering pulses of different energy modalities to tissue. As described herein, the logic flow diagram 4800 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram 4800 of FIG. 75, initially, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the processor 502 signals the waveform generator 504 to deliver the pulse sequences discussed herein. In accordance with the method, the processor 502 activates 4802 an RF energy modality of the surgical instrument 108 to drive RF energy through electrodes located in the clamp arm 145 of the end effector 125. The processor 502 deactivates 4804 the RF energy modality upon the expiration of a first predetermined period T₁. The processor 502 activates 4806 an ultrasonic energy modality of the surgical instrument 108 to drive the ultrasonic blade 149. The processor 502 deactivates 4808 the ultrasonic energy modality upon the expiration of a second predetermined period T₂.

Techniques for Simultaneously Delivering Blasts of Ultrasonic and RF Energy in a Combination Ultrasonic/RF Surgical Instrument

In one aspect, the present disclosure provides a technique for delivering a combination simultaneous blast of RF and ultrasonic energy to an end effector of a surgical instrument by controlling the power delivered to an end effector from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or a surgical instrument, such as the surgical instrument 108 (FIGS. 1-3). In accordance with the present technique, a combination simultaneous blast of RF and ultrasonic energy can be delivered to an end effector of a surgical instrument can be varied based on properties or parameters of tissue interacting with the end effector. For conciseness and clarity of disclosure, the techniques for delivering a combination simultaneous blast of RF and ultrasonic energy to the end effector will be described with reference to the multifunction surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

FIGS. 76-80 illustrate aspects of delivering multiple energy modalities to tissue. In one aspect the first energy modality is RF energy and the second energy modality is ultrasonic energy. There are many benefits to a surgical device that is capable of delivering both RF and ultrasonic energy. A surgical instrument capable of delivering both modalities provides stronger seals and can cut tissue without the need of a separate knife. The following disclosure provides multiple pulsing techniques than can be utilized for vessel sealing. These techniques employ tissue impedance measurements, current measurements, can seal only, and can seal and cut tissue.

The various aspects described below provides simultaneous activation of multiple energy modalities such as RF and ultrasonic energy modalities. Initially both RF and ultrasonic modalities are delivered to tissue. The RF energy modality is utilized for the first portion of the seal. After a set amount of time T₁, based off the RF impedance Z_(T) detected, the ultrasonic modality is terminated. A short blast of ultrasonic energy at the beginning of the seal cycle provides benefits to sealing, as it aids in heating the ultrasonic blade and subsequently the tissue surface in contact with the blade while the electrode is simultaneously heating the tissue surface in contact with the RF electrodes.

These techniques may be implemented using multiple generators, one generator configured to deliver RF energy and another generator configured to deliver ultrasonic energy. Alternatively, these techniques may be implemented with a single generator configured to deliver both RF and ultrasonic energy. In other aspects, these techniques may be implemented with a single generator that is configured to deliver RF and ultrasonic energy simultaneously through a single output port. These techniques comprise simultaneous pulsing of RF and ultrasonic energy modalities to create strong seals. Multiple configurations of pulsing are disclosed. Multiple configurations of the simultaneous techniques are disclosed.

FIG. 76 is a logic flow diagram 4900 of one aspect of a process of applying simultaneous activation of different energy modalities to tissue. As described herein, the logic flow diagram 4900 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 4900 of FIG. 76, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the generator 500 delivers the simultaneous energy modalities. The total seal time 4902 is shown along a vertical axis.

Once tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108, the processor 502 signals the waveform generator 504 to deliver the pulse sequences discussed herein. In accordance with the logic flow diagram 4900 of FIG. 76, the RF energy modality application process 4904 is shown on the left and ultrasonic energy modality application process 4916 is shown on the right. The processor 502 activates 4996 the RF energy modality at the same time that the ultrasonic energy modality is activated 4918. Once the RF energy modality is activated 4906, the processor 502 signals the waveform generator 504 to deliver 4908 RF energy in accordance with a variety of RF sealing techniques, including RF sealing techniques described herein in connection with the logic diagram 5400 shown FIG. 81. Turning back to FIG. 76, the processor 502 activates 4920 the ultrasonic energy modality at a constant power level. During the simultaneous application of the RF and ultrasonic energy modalities, the processor 502 measures the RF tissue impedance Z_(tissue) and when the RF tissue impedance Z_(tissue) meets ore exceeds an ultrasonic termination impedance Z_(US-term) (see FIG. 77) it is provided 4910 as feedback to the processor 502 to signal 4922 the waveform generator 504 and amplifier 506 to terminate 4924 delivery of ultrasonic energy to the end effector 125. Meantime, the RF energy modality is continuously delivered until an RF termination impedance Z_(RF-term) is reached 4912 at which point the processor 502 signals the waveform generator 504 to terminate 4914 delivery of RF energy. The short blast of the ultrasonic energy at the beginning of the seal cycle provides benefits to sealing, as it aids in heating the ultrasonic blade 149 and subsequently the tissue surface in contact with the blade 149 while the electrode in the clamp arm 145 is simultaneously heating the tissue surface in contact with the electrode. As previously discussed, the tissue impedance is determined by the processor 502 by dividing the voltage applied to the end effector 125 by the current delivered to the end effector 125. For example, the processor 502 can determine the tissue impedance by dividing the voltage sensed by the second voltage sensing circuit 524 by the current sensed by the current sensing circuit 514.

FIG. 77 is a graphical representation of RF Impedance versus Time in connection with the logic flow diagram 4900 of FIG. 76 to illustrate the ultrasonic termination impedance. The horizontal axis is time (ms) and the vertical axis is RF impedance (Ohms). The tissue impedance Z_(tissue) curve 5002 is monitored during the sealing period utilizing the RF energy. When the tissue impedance Z_(tissue) reaches the ultrasonic termination impedance Z_(US-term) 5004 the ultrasonic power is terminated and when the tissue impedance Z_(tissue) reaches the RF termination impedance Z_(RF-term) 5006 the RF energy is terminated.

FIG. 78 illustrates an example of the quality of a seal 5102 made in a vessel 5100 using the simultaneous activation of RF and ultrasonic energy modalities as described in connection with FIGS. 67 and 68. The main advantage of simultaneous activation of RF and ultrasonic energy modalities is that the ultrasonic energy heats up the ultrasonic blade 149 and helps to create a reduction in the difference in thermal mass between the ultrasonic blade 149 and the electrode in the clamp arm 145. During a non-simultaneous activation seal cycle utilizing both RF and ultrasonic modalities, a challenge is posed to create a strong seal with varying thermal masses on either side of the end effector 125 jaw.

FIG. 79 is a graphical representation 5200 of seal burst pressure of carotid bundles versus an RF only seal and a simultaneous RF/ultrasonic seal as described in connection with FIGS. 67-69. The horizontal axis is an RF seal only boxplot 5202 and a simultaneous RF/ultrasonic boxplot 5204. The boxplots 5202, 5204 demonstrate the tissue effect advantages described ion connection with the simultaneous RF/ultrasonic energy modality activation process 4100 shown in connection with FIG. 76 where simultaneously heating the ultrasonic blade and electrode provides a high quality 5102 in a vessel as shown in FIG. 78.

FIG. 80 is a logic flow diagram 5300 of a process of simultaneous activation of RF and ultrasonic energy modalities. As described herein, the logic flow diagram 5300 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 5300 of FIG. 80, initially, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the processor 502 signals the waveform generator 504 to deliver the pulse sequences discussed herein. In accordance with the logic flow diagram 5300, the processor 502 simultaneously activates 5302 an RF energy modality and an ultrasonic energy modality of the surgical instrument 108. The processor 502 monitors 5304 the tissue impedance using RF energy modality. When the tissue impedance is equal to or greater than a first termination impedance, the generator 500 deactivates 5306 the ultrasonic energy modality of the surgical instrument 108. The RF energy modality is delivered until the tissue impedance is equal to or greater than a second termination impedance, at which time the processor 502 deactivates 5308 the RF energy modality of the surgical instrument 108 and the tissue seal is complete.

In some aspects utilizing a pulsed drive signal, a generator, such as, for example, one of generators 102, 200, 300, 400, 500 described in connection with FIGS. 1-3 and 5-8, may apply one or more composite load curves to the drive signal, and ultimately to the tissue. Composite load curves may define a level of power to be delivered to the tissue as a function of a measured tissue property or properties (e.g., impedance). Composite load curves may, additionally, define pulse characteristics, such as pulse width, in terms of the measured tissue properties.

FIG. 81 illustrates one aspect of a logic diagram 5400 for the selection and application of composite load curves by any one of generators 102, 200, 300, 400, 500. It will be appreciated that the logic diagram 5400 may be implemented with any suitable type of generator or surgical device. According to various aspects, the logic diagram 5400 may be implemented utilizing an electrosurgical instrument, such as the electrosurgical instrument 106 described above with respect to FIG. 1, an ultrasonic surgical instrument 104 described above with respect to FIG. 1, or a combination surgical instrument 108 described above with respect to FIGS. 1-3.

Referring back to FIG. 81, a control process 5402 may be executed, for example by a digital device of the generator 102 to select and apply composite load curves 5406, 5408, 5410, 5412. The control process 5402 may receive a time input from a clock 5404 and may also receive loop input 5424 from sensors 5418. The loop input 5424 may represent properties or characteristics of the tissue that may be utilized in the control process 5402 to select and/or apply a composite load curve. Examples of such characteristics may comprise, for example, current, voltage, temperature, reflectivity, force delivered to the tissue, resonant frequency, rate of change of resonant frequency, etc. The sensors 5418 may be dedicated sensors (e.g., thermometers, pressure sensors, etc.) or may be software implemented sensors for deriving tissue characteristics based on other system values (e.g., for observing and/or calculating voltage, current, tissue temperature, etc., based on the drive signal). The control process 5402 may select one of the composite load curves 5406, 5408, 5410, 5412 to apply, for example based on the loop input 5424 and/or the time input from the clock 5404. Although four composite load curves are shown, it will be appreciated that any suitable number of composite load curves may be used.

The control process 5402 may apply a selected composite load curve in any suitable manner. For example, the control process 5402 may use the selected composite load curve to calculate a power level and one or more pulse characteristics based on tissue impedance (e.g., currently measured tissue impedance may be a part of, or may be derived from, the loop input) or resonant frequency characteristics of a ultrasonic surgical instrument 104. Examples of pulse characteristics that may be determined based on tissue impedance according to a composite load curve may include pulse width, ramp time, and off time.

At set point 5414, the derived power and pulse characteristics may be delivered to the drive signal. In various aspects, a feedback loop 5422 may be implemented to allow for more accurate modulation of the drive signal. At the output of the set point 5414, the drive signal may be provided to an amplifier 5416, which may provide suitable amplification. The amplified drive signal may be provided to a load 5420 (e.g., via sensors 5418). The load 5420 may comprise the tissue, the surgical instrument 104, 106, 108, and/or any cable electrically coupling a generator with the surgical instrument 104, 106, 108 (e.g., cables 142, 144, 146).

In various aspects the state of coagulation may be determined using neural networks that are configured to take a plurality of factors into account. In some aspects, a generator may be configured to drive both ultrasonic and electrosurgical systems and include a nested neural network to identify whether the generator is presented with a true short circuit vs. a low impedance tissue. In addition, in some aspects, to assist in the detection of short circuits, the neural network may be configured to track and store at least the following factors: a. Measured resistance/impedance; b. Drive current (RMS); c. Drive Voltage (RMS); and d. Moving average of measured impedance. In some aspects, the neural network will be thought to in order to be capable of discerning between a true short and low impedance tissue. In other aspects, a neural network may be programmed to identify properties in metal, tissues, and other non-tissue elements. The neural network also may be configured to transmit the exploratory pulse to the transducer. In addition, new developments or additional programs, including receiving feedback from the attempts to detect short circuits, may be incorporated back into the neural network to increase its situational awareness and effectively better learn how to detect a true short circuit. Wth confirmation of a short circuit both by RF and ultrasonic functionality, this can allow for less time spent getting repeat errors on RF and faster transection on low impedance tissue. An example of a neural network is described in connection with FIG. 82.

FIG. 82 illustrates one aspect of a neural network 5500 for controlling a generator. FIG. 73 illustrates one aspect of an artificial neural network 5500 for generating an estimated temperature T_(est) resulting from an application of ultrasonic energy using an ultrasonic surgical instrument, such as the ultrasonic surgical instruments 104, 106, 108 (FIGS. 1-3). In certain aspects, the neural network 5500 may be implemented in the processor and/or the programmable logic device of the generator 102 (FIG. 1). The neural network 5500 may comprise an input layer 5502, one or more nodes 5504 defining a hidden layer 5506, and one or more nodes 5508 defining an output layer 5510. For the sake of clarity, only one hidden layer 5506 s shown. In certain aspects, the neural network 5500 may comprise one or more additional hidden layers in a cascaded arrangement, with each additional hidden layer having a number of nodes 5504 that may be equal to or different from the number of nodes 5504 in the hidden layer 5506.

Each node 5504, 5508 in the layers 5502, 5510 may include one or more weight values w 5512, a bias value b 5514, and a transform function f 5516. In FIG. 82, the use of different subscripts for these values and functions is intended to illustrate that each of these values and functions may be different from the other values and functions. The input layer 5502 comprises one or more input variables p 5518, with each node 5504 of the hidden layer 5506 receiving as input at least one of the input variables p 5518. As shown in FIG. 82, for example, each node 5504 may receive all of the input variables p 5518. In other aspects, less than all of the input variables p 5518 may be received by a node 5504. Each input variable p 5518 received by a particular node 5504 is weighted by a corresponding weight value w 5512, then added to any other similarly weighted input variables p 5518, and to the bias value b 5512. The transform function f 5516 of the node 5504 is then applied to the resulting sum to generate the node's output. In FIG. 82, for example, the output of node 5504-1 may be given as f₁(n₁), where n₁=(w_(1,1)·p₁+w_(1,2)·p₂+ . . . +w_(1,j)·p_(ij)+b₁.

A particular node 5508 of the output layer 5510 may receive an output from one or more of the nodes 5504 of the hidden layer 5506 (e.g., each node 5508 receives outputs f₁(⋅), f₂(⋅), . . . , f_(i)(⋅) from respective nodes 5504-1, 5504-2, . . . , 5504-i in FIG. 82), with each received output being weighted by a corresponding weight value w 5512 and subsequently added to any other similarly weighted received outputs, and to a bias value b 5514. The transform function f 5516 of the node 5508 is then applied to the resulting sum to generate the node's output, which corresponds to an output of the neural network 5500 (e.g., the estimated temperature T_(est) in the aspect of FIG. 82). Although the aspect of the neural network 5500 in FIG. 82 comprises only one node 5508 in the output layer 5510, in other aspects the neural network 5500 may comprise more than one output, in which case the output layer 5510 may comprise multiple nodes 5508.

In certain aspects, the transform function f 5516 of a node 5504, 5508 may be a nonlinear transfer function. In one aspect, for example, one or more of the transform functions f 5516 may be a sigmoid function. In other aspects, the transform functions f 5516 may include a tangent sigmoid, a hyperbolic tangent sigmoid, a logarithmic sigmoid, a linear transfer function, a saturated linear transfer function, a radial basis transfer function, or some other type of transfer function. The transform function f 5516 of a particular node 5504, 5508 may be the same as, or different from, a transform function f 5516 in another node 5504, 5508.

In certain aspects, the input variables p 5518 received by the nodes 5504 of the hidden layer 5506 may represent, for example, signals and/or other quantities or conditions known or believed to have an effect on the temperature or heating resulting from an application of ultrasonic energy. Such variables may comprise, for example, one or more of: drive voltage output by the generator 102, drive current output by the generator 102, drive frequency of the generator output 102, drive power output by the generator 102, drive energy output by the generator 102, impedance of the ultrasonic transducer 120, and time duration over which ultrasonic energy is delivered. Additionally, one or more of the input variables p 5518 may be unrelated to outputs of the generator 102 and may comprise, for example, characteristics of the end effector 122, 125 (e.g., blade tip size, geometry, and/or material) and a particular type of tissue targeted by the ultrasonic energy.

The neural network 5500 may be trained (e.g., by changing or varying the weight values w 5512, the bias values b 5514, and the transform functions f 5516) such that its output (e.g., estimated temperature T_(est) in the aspect of FIG. 82) suitably approximates a measured dependency of the output for known values of the input variables p 5518. Training may be performed, for example, by supplying known sets of input variables p 5518, comparing output of the neural network 5500 to measured outputs corresponding to the known sets of input variables p 5518, and modifying the weight values w 5512, the bias values b 5514, and/or the transform functions f 5516 until the error between the outputs of the neural network 5500 and the corresponding measured outputs is below a predetermined error level. For example, the neural network 5500 may be trained until the mean square error is below a predetermined error threshold. In certain aspects, aspects of the training process may be implemented by the neural network 5500 (e.g., by propagating errors back through the network 5500 to adaptively adjust the weight values w 5512 and/or the bias values b 5514).

FIG. 83 illustrates an example graph of a curve 5600 of impedance (|Z|) versus time (t) showing the termination impedance at which a proper tissue seal is achieved using RF energy. The curve 5600 provides time in seconds along the horizontal axis and impedance in Ohms along the vertical axis. The impedance versus time curve 5600 is described in three sections 5602, 5604, and 5606. Section one 5602 represents the initial impedance of the tissue from a time 5608 just after energy is applied to the tissue to a time 5610 when the tissue impedance drops to a minimum value as shown in section two 5604. Section one 5602 of the curve 5600 decreases for an initial impedance |Z| value until it stabilizes to a minimum impedance in the second section 5604 of the curve 5600. After energy is delivered to the end effector and applied to the tissue for a certain period (e.g., 4.5 seconds as shown) the moisture content of the tissue evaporates causing the tissue to dry out and the impedance of the tissue to rise in section three 5606 of the curve until the termination impedance |Z_(T)| is reached, at which point in time, T_(o), the energy to the end effector is shut off. The portion of the curve 5600 in section three 5606 (shown in dashed line) represents the increase in tissue impedance |Z| that would result if the energy were be applied continuously instead of being shut off at the termination impedance |Z_(T)| point.

Once the termination impedance |Z_(T)| has been reached, the generator may switch from delivering RF energy to ultrasonic energy. The termination impedance |Z_(T)| can be a fixed value based on the instrument's electrode and compression properties or it can be a variable that depends on factors measured during the grasping and coagulation cycle such as: amount of tissue grasped, initial impedance and minimum impedance. It also can be a variable dependent on various slopes of impedance, energy delivery at various points in the coagulation cycle such as minimum impedance, and/or inflection points, and combinations thereof.

Tissue impedance as a function of time is a continuous differentiable function of time. It can be shown, through system identification techniques and system parameter optimization that a model exists which can model the relationship of the power input to tissue. The form of the model is:

$\begin{matrix} {\overset{¨}{Z} = \left\{ \begin{matrix} {{{kZ} + {b_{1}\overset{.}{Z}} + {{c_{1}\left( {W - c_{2}} \right)}\mspace{14mu} {if}\mspace{14mu} \overset{.}{Z}}} < 0} \\ {{{kZ} + {b_{2}\overset{.}{Z}} + {{c_{1}\left( {W - c_{2}} \right)}\mspace{14mu} {if}\mspace{14mu} \overset{.}{Z}}} \geq 0} \end{matrix} \right.} & {{Equation}\mspace{14mu} 3} \end{matrix}$

In Equation 3, Z is the impedance measured (estimated from known current and voltage) across the tissue, Ż and {umlaut over (Z)} are the first and second derivatives of the tissue impedance. k, b₁, b₂ c₁, and c₂ are the parameters to be estimated. W is the work applied to the tissue in Joules. Using a combination of downhill simplex and global based optimization techniques, such as, for example evolutionary processes, particle swarm optimization, and simulated annealing. The parameters can be estimated in quasi-real time, which are below user noticeable time periods.

FIG. 84 displays curves 5702, 5704 of tissue impedance versus time of tissue impedance with 40 W of RF power delivered to tissue using a downhill simplex technique for a model of tissue 5702 and experimental data 5704. As shown in FIG. 84, the curves 5702, 5704 are similar to the curve 2500 shown in FIG. 83.

As demonstrated by the curves of FIG. 84, constant power may be applied to tissue while in the time period 0 seconds to approximately 8.8 seconds, the curves 5702, 5704 have a distinct shape that may be referred to as a “bathtub,” due to the characteristic bathtub shape of the tissue impedance as a function of time while power is applied to the tissue during the sealing process. Once system identification has occurred during the tissue “bathtub” period to estimate k, b₁, b₂, c₁, and c₂ of Equation 1 above, a post “bathtub” impedance control technique can be configured for tissue interacting with the end effector 125 of the surgical instrument 108.

One post “bathtub” impedance control technique utilizes parameter estimation to determine tissue characteristics. In one aspect, the parameters estimated during the “bathtub” phase may relate to certain tissue properties, such as, for example tissue type, tissue amount, and tissue state. A predetermined controller can be selected from a range of controllers that best match the parameters estimated based on a lookup table

Another post “bathtub” impedance control technique utilizes a linear quadratic controller (LQR) with precompensation. A linear quadratic controller is a well-known and used controller which can be designed in real time and will result in optimal control of tissue impedance and the rate of change of impedance. In one aspect, an LQR controller can be implemented in the following form:

$\begin{matrix} {W = {{{Nb}*r} - {K\begin{bmatrix} Z \\ \overset{.}{Z} \end{bmatrix}} + c_{2}}} & {{Equation}\mspace{14mu} 4} \end{matrix}$

It is assumed that K is the control gain and r is a desired reference set point and Nb is a precompensation gain to prevent steady state error. From this system, rate rise can be controlled explicitly. The second order differential equation shown in Equation 4 is to be reduced to two first order equations for each value of b₁ and b₂. However, if it is assumed that the goal of post “bathtub” energy application will result in Ż>0 ∀ t>0 (that is, Ż>0 for all time values after the start of energy application when t=0) then it can be assumed that the controller must be designed for b=b₂. The reduction to first order is shown in Equation 5:

Let Z=U ₁ and Ż=U ₂

then through substitution:

$\begin{matrix} {\begin{bmatrix} {\overset{.}{U}}_{1} \\ {\overset{.}{U}}_{2} \end{bmatrix} = {{\begin{bmatrix} 0 & 1 \\ k & b \end{bmatrix}\begin{bmatrix} U_{1} \\ U_{2} \end{bmatrix}} + {\begin{bmatrix} 0 \\ 1 \end{bmatrix}\left( {W - c_{2}} \right)}}} & {{Equation}\mspace{14mu} 5} \end{matrix}$

For such a system, the optimal control input K can be found by reducing a cost function of a particular form and solving the Ricatti algebraic equation. The control cost function to be reduced has the form given in Equation 4 and is common to all LQR controllers.

$\begin{matrix} {J = {\int_{0}^{\infty}{\left( {{\left\lbrack {U_{1}\mspace{14mu} U_{2}} \right\rbrack {Q\begin{bmatrix} U_{1} \\ U_{2} \end{bmatrix}}} + {\left\lbrack {0\mspace{14mu} W} \right\rbrack {R\begin{bmatrix} 0 \\ W \end{bmatrix}}} + {{2\left\lbrack {U_{1}\mspace{14mu} U_{2}} \right\rbrack}{N\begin{bmatrix} 0 \\ W \end{bmatrix}}}} \right){dt}}}} & {{Equation}\mspace{14mu} 6} \end{matrix}$

R, N, and Q are predetermined constant matrices related to the cost function being reduced and controller performance. They are selected by the design engineer to regulate the controller's performance. When this process is completed, K is given by:

K=R ⁻¹(B ^(T) P(t)+N ^(T)  Equation 7

In Equation 5, P is the solution to the algebraic Riccati equation in Equation 8:

A ^(T) P+PA−(PB+N)R ⁻¹(B ^(T) P+N ^(T))+Q=0  Equation 8

According to one aspect, upon fitting a model to experimental data points, such as that show in FIG. 84 for curves 5702 and 5704 respectively, Equation 5 may be used to create an optimal controller that holds impedance at a steady state value, r=250 Ohm. FIG. 85 displays curves 5802 and 5804 that represent the modeled data and the experimental data, respectively. As shown in FIG. 85, the controller performed as expected on a fitted tissue model where the desired impedance 5806, Z, is held at 250 Ohm. For the controller shown in FIG. 85, K=[1.9237 4.3321] and Nb=[26.9532]. A range of appropriate gains exist and can be determined. Similarly, a range of feasible gains for the model development can also be determined.

Additionally, a controller also may be configured to operate as a tracking controller to manipulate Ż by updating the reference r appropriately in time. An example of such a controller is illustrated in FIG. 86, where curves 5902 and 5904 that represent the modeled data and the experimental data, respectively, and line 5906 is the desired impedance for one aspect of a tracking controller. As shown in FIG. 86, a desired tissue impedance, where the desired impedance is based on a rate of change of the tissue impedance, may be achieved. Steady state performance with a tracking controller can be improved by incorporating an integrator to the system of equations shown by Equation 7.

FIG. 87 is a logic flow diagram 6000 of a method for identifying a tissue type and developing a control process to control the application of an energy modality to the tissue according to tissue impedance. As described herein, the logic flow diagram 6000 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 6000 shown in FIG. 87, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the generator 500 may not be able to determine a tissue type located between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125. In accordance with the method, the processor 502 signals the waveform generator 504 to deliver 6002 an energy modality to the end effector 125 of the surgical instrument 108. The processor 502 measures 6004 tissue impedance. Application of the energy modality ceases 6006 upon the processor 502 determining that the tissue impedance matches a predetermined threshold tissue impedance. The processor 502 estimates 6008 at least one tissue parameter based at least partially on the measured tissue impedance. According to various aspects, the at least one tissue parameter comprises a tissue type, a tissue amount, a tissue state, or a combination thereof. The processor 502 develops 6010 a parameterized tissue model based on the at least one estimated tissue parameter and generates 6012 a control technique for application of the energy modality based on the parameterized tissue model. Accordingly, the energy modality may be applied to another tissue portion according to the control process.

In another aspect, generating the control process may comprise correlating specific tissue characteristics with the application of the energy modality to the tissue. Furthermore, the control process may be generated in real time such that it readily available for use on further applications to tissue. In addition, the control process may be configured to apply the energy modality so the tissue impedance matches a predetermined threshold value or a predetermined rate of change.

Ultrasonic Output Controlled by RF Impedance Trajectory

In one aspect, the present disclosure provides ultrasonic output controlled by RF impedance trajectory to control the power output from a generator, such as any one of the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), or the surgical instrument 108 (FIGS. 1-3). The power delivered to an end effector of a surgical instrument can vary based on the tissue RF impedance trajectory. For conciseness and clarity of disclosure, the techniques for ultrasonic output controlled by RF impedance trajectory to control the power output from a generator will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

According to one aspect, a surgical instrument may uses an RF energy modality to sense tissue characteristics, such as impedance, and the changes of the tissue characteristics to modulate the output power of an ultrasonic tissue treating system. Specifically, the output power of a surgical instrument may be modulated as a function of a desired impedance trajectory where the impedance trajectory results in a desired tissue effect or outcome. The RF output may be therapeutic, e.g. tissue treating, or sub-therapeutic, e.g. sensing only. Further, the RF output may be applied to the tissue and the voltage and current, or representations of the voltage and current, are measured or estimated. In addition, the impedance may be calculated by determining the ratio of the voltage to the current.

FIG. 88 is a logic flow diagram 6100 of a method for treating tissue. As described herein, the logic flow diagram 6100 may be implemented in the generator 500, the multifunction surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram 6100 shown in FIG. 88, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108. In accordance with the method, the processor 502 signals the waveform generator 504 to deliver 6102 an energy modality to the end effector 125 of the surgical instrument 108. According to various aspects, the energy modality may be an RF energy modality or an ultrasonic energy modality, or a blended combination thereof, and the amplitude may be a therapeutic amplitude, a sub-therapeutic amplitude, or a combination thereof. The processor 502 measures 6104 tissue impedance and signals the waveform generator 504 to modulate 6106 the delivery of the selected energy modality based on the measured tissue impedance. Ultimately, the processor 502 signals the waveform generator 504 to cease 6108 the application of the energy modality upon meeting or exceeding a termination impedance threshold that corresponds to a tissue parameter, such as, for example, that the seal is complete. The application of the energy modality may cease upon the tissue impedance matching a predetermined threshold value of tissue impedance or a predetermined threshold rate of change of tissue impedance. The impedance may be determined by the processor 502 by dividing the output of the second voltage sensing circuit 524 is coupled across the terminals labeled ENERGY2/RETURN by the output of the current sensing circuit 514 is disposed in series with the RETURN leg of the secondary side of the power transformer 508 as shown in FIG. 8.

In accordance with the logic flow diagram 6100, the surgical instrument 108 may further determine that the tissue is sealed based on measuring at least one of an initial tissue impedance, an initial jaws-aperture of an end effector, a current tissue impedance, a rate of change of tissue impedance, an amount of energy driven into the tissue, a transaction time for the energy modality and/or determining a state of the tissue based on the measured tissue impedance of the tissue. The state of the tissue may comprise one of coagulated, sealed, or cut, for example.

Modulating application of the energy modality based on the measured tissue impedance may comprise applying the energy modality to cause the tissue impedance to change according to a predetermined course. In various aspects, the predetermined course comprises a predetermined threshold value of tissue impedance of the tissue or a predetermined threshold rate of change of tissue impedance of the tissue. In another aspect, modulating application of the energy modality based on the measured tissue impedance comprises modifying an output power of a generator, modifying an output waveform of the generator, selecting another energy modality to apply to the tissue, modifying the termination parameter. Additionally, the energy modality may be a first energy modality and the method further comprises applying a second energy modality to tissue at a second amplitude. The first energy modality may be an RF energy modality and the second energy modality may be an ultrasonic energy modality

In another aspect, the generator 500 may comprise an ultrasonic output (ENERGY1/RETURN) configured to deliver a drive signal to an ultrasonic transducer 120 coupled to an ultrasonic blade 149 of the surgical instrument 108. The generator 500 also may comprise an RF output (ENERGY2/RETURN) configured to deliver an electrosurgical RF drive signal to at least one electrode located in the arm 145 of the surgical instrument 108. The generator 500 also may comprise sensing circuitry such as a second voltage sensing circuit 524 and a current sensing circuit 514 configured to measure tissue impedance, and a processor 502 configured to determine whether a tissue reaction has occurred based on a measured tissue impedance of the tissue and a predetermined change in the measured tissue impedance. The waveform generator 504 and amplifier 506 are controlled by the processor 502 to provide the necessary ultrasonic energy or RF energy modalities at the respective outputs of the generator 500 labelled (ENERGY1/RETURN) and (ENERGY2/RETURN).

The tissue treating portion of the ultrasonic blade 149 is configured to apply ultrasonic energy to tissue to affect treatment of the tissue and the ultrasonic amplitude of the tissue treating portion is controlled by the processor 502. The at least one electrode is configured to receive RF energy from the generator 500 output and to apply the RF energy to the tissue via the electrode. The amplitude of the electrosurgical RF energy is controlled by the processor 502. In one aspect, the tissue reaction determination corresponds to a boiling point of fluid in the tissue. Moreover, the processor 502 may be configured to generate a target impedance trajectory as a function of the measured tissue impedance and a predetermined desired rate of change of tissue impedance, and the tissue reaction determination. The target impedance trajectory includes a plurality of target impedance values for each of a plurality of points of time. Furthermore, the processor 502 may be configured to drive tissue impedance along the target impedance trajectory by adjusting the ultrasonic amplitude of the tissue treating portion of the ultrasonic blade 149 to substantially match the tissue impedance to a predetermined tissue impedance value for a predetermined time period.

Also disclosed herein are control processes for dynamically changing the energy delivered from a generator based on tissue impedance of tissue engaged with an end effector, such as an end effector of a surgical instrument 108. According to one aspect, a process for controlling the power output from a generator, such as the generator 500 of FIG. 8, that is delivered to the end effector 125 of the surgical instrument 108 can include an input that represents tissue impedance of tissue engaged with the end effector 125 of the surgical instrument 108. During the tissue treatment process, the energy profile from the generator 500 can be dynamically changed between RF energy and ultrasonic energy based on the tissue impedance. This allows the generator 500 to switch from RF energy to ultrasonic energy based on the tissue impedance of the tissue under treatment. The tissue impedance is related to the creation of a proper coagulation seal, for example, when RF energy is delivered from the generator 500 to the end effector 125 of the surgical instrument 108, such that RF energy should be used when there is sufficient tissue impedance. Thus, in one aspect, when a particular tissue impedance is not found and there is not a sufficient tissue impedance to activate a RF energy modality on the tissue for proper coagulation or seal, ultrasonic energy may be delivered to the end effector 125 to raise the tissue impedance to a level where the RF energy modality can be delivered to complete the seal.

Energy parameters are configured to be loaded into the generator 500, and can include a plurality of different parameters, including but not limited to voltage, current, power, and one or more processes for use in treating tissue. These parameters can be related to the RF energy and ultrasonic energy that can be delivered from the generator 500 and accordingly, may be based on tissue impedance of tissue engaged with a surgical device. The energy parameters can include information such as maximum and/or minimum values to be used to control the energy delivered from the generator 500. The energy parameters can be stored in a variety of locations, including an EEPROM on the surgical instrument 108 or some other non-volatile memory. In addition, there can be multiple sets of energy parameters. For example, there can be a first set of energy parameters that are used to optimize tissue transection, and a second set of energy parameters that are used to optimize tissue spot coagulation. It will be understood that there can be any number of set of energy parameters that correspond to various types of tissue treatments to allow the generator to switch between the various sets of energy parameters based on the necessary tissue treatments.

It will be understood that various combinations of information can be used to determine which set of energy parameters are to be used during tissue treatment. For example, the aperture of the end effector and calculated tissue impedance can be used to determine which set of energy parameters are needed to control the energy being delivered from the generator.

In another aspect, a process for controlling the power output from a generator, such as the generator of FIG. 8, that is delivered to the end effector of the surgical instrument can include an input that includes inputs related to the size of the tissue being treated by the end effector of the surgical instrument. The energy being delivered from the generator can be dynamically changed during the procedure between RF and ultrasonic energy to achieve dissection and coagulation of a large tissue based on a determination of the effectiveness of the RF energy in coagulating the large tissue. A determination of the effectiveness of the RF energy in coagulating a tissue includes a calculation of tissue impedance, as explained above, of the large tissue interacting with the end effector, which is used to determine the type of energy being delivered by the generator to the end effector.

Technique for Switching Between RF and Ultrasonic Energy Based on Tissue Impedance

In one aspect, the present disclosure provides techniques for switching between RF and ultrasonic energy based on tissue impedance. The power output from a generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), is delivered to an end effector of a surgical instrument can be controlled based on the tissue impedance. The energy profile of the power output of the generator is dynamically switched between RF and ultrasonic energy modalities based on the tissue impedance to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for switching between RF and ultrasonic energy based on tissue impedance will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The following description provides techniques for measuring tissue impedance and dynamically switching the energy profile of the generator between RF and ultrasonic energy modalities based on the tissue impedance during the procedure. To provide a better seal, it may be desirable to operate a “combination” RF/ultrasonic instrument 108 such that the instrument transition from a tissue coagulation mode to a tissue cut mode during an application of the instrument 108 on tissue. Disclosed is a way to automatically transition from the RF (coagulation or seal) mode to the ultrasonic (cut or transection) mode. In various RF sealing techniques, the RF energy is applied with the goal of driving the tissue impedance to a particular level, called the “termination” impedance. It has been demonstrated that an adequate seal is achieved if an RF sealing technique is able to drive the tissue impedance to this termination impedance.

In order to determine the tissue impedance being treated by the end effector 125 of the surgical instrument 108, the tissue impedance must be calculated. The calculated tissue impedance is compared to a threshold value, as will be discussed in more detail below. The calculated tissue impedance is used by a technique to control the energy being delivered from the generator 500 to the surgical instrument 108 to allow the energy to switch between RF and ultrasonic energy when the tissue impedance reaches the threshold level. In one form, the tissue impedance is described by dividing the voltage measurement by the current measurement. More generally, impedance is the ratio of the voltage vector and the current vector and results in a complex number with the real component R and the imaginary component X dependent on both tissue properties and the frequency and spectra of the applied stimulus. This number also can be expressed in the form of a magnitude, |Z| and phase (I). Most calculations of tissue impedance ignore the small contribution of the phase difference between the voltage and current and presume that the magnitude of the impedance vector |Z| is essentially equivalent to the real component of the impedance, R. For purposes of description, the term R and Z indicating tissue impedance will be used interchangeably though it should be noted that sensing of tissue impedance implies that the impedance vector is the general form and any combination of magnitude, phase, real and imaginary components of this vector for determining tissue properties, control of energy delivery and the like is implied by this disclosure.

For example, when utilizing the surgical instrument 108 that can automatically transition between RF and ultrasonic energy, RF energy can be applied to the tissue utilizing the end effector 108 to drive the tissue impedance of the tissue to a particular level, such as a termination impedance. The termination impedance is the tissue impedance level of the tissue that substantially ensure that the RF energy has achieved adequate coagulation of the tissue.

FIG. 89 is a graphical depiction of a tissue impedance function 6200 represented as tissue impedance |Z| (Ohms) as a function of time (Sec) and showing a termination impedance at which a proper tissue seal is achieved utilizing RF energy. The tissue impedance function 6200 shows the termination impedance Z_(T) 6216 at which a proper tissue seal is achieved utilizing RF energy. Time in seconds is shown along the horizontal axis and impedance in Ohms is shown along the vertical axis. The tissue impedance function 6200 can be described in three sections. In section one 6202, the tissue impedance function 6200 represents the initial impedance 6208 of the tissue from a time just after RF energy is applied to the tissue to a time when the tissue impedance drops to a minimum value as shown in the section two 6204. In section one 6202 of the tissue impedance function 6200, the tissue impedance drops from an initial value 6208 and decreases, e.g., has a negative slope, until it reaches a first inflection point 6210 and stabilizes to a minimum impedance 6212 in the second section 6204 of the tissue impedance function 6200 where the tissue impedance function flattens 6200 flattens out. After energy is applied to the tissue for a certain period (e.g., 4.5 seconds as shown) the moisture content of the tissue evaporates causing the tissue to dry out and causes the tissue impedance to begin rising, e.g., positive slope, at a second inflection point 6214 in section three 6206 of the tissue impedance function 6200 until the tissue impedance reaches a predetermined termination impedance 6216, at which point in time the RF energy to the end effector is shut off. The last portion 6218 of the tissue impedance function 6200 in section three 6206 (shown in dashed line) represents the increase in tissue impedance Z that would result if the RF energy were to be applied continuously instead of being shut off at the termination impedance 6216 point. The tissue impedance function 6200 may be referred to as the “bathtub” zone in a tissue sealing process due to its characteristic shape.

Once the termination impedance 6216 is reached, the generator 500 can switch from delivering RF energy to delivering ultrasonic energy to the end effector 125. The termination impedance 6216 can be a fixed value based on the electrode and compression properties or it can be a variable that depends on factors measured during the grasping and coagulation cycle such as amount of tissue grasped, initial impedance, and minimum impedance. It also can be a variable dependent on various slopes of impedance, energy delivery at various points in the coagulation cycle such as minimum impedance, and/or inflection points, and combinations thereof.

FIG. 90 is a logic flow diagram 6300 to control the generator 500 to switch between RF and ultrasonic energy upon reaching a predetermined termination impedance. As described herein, the logic flow diagram 6300 may be implemented in the generator 500, the surgical instrument 108, or a combination thereof. With reference now to the logic flow diagram shown in FIG. 90, the processor 502 determines the tissue impedance as described herein. For example, the processor 502 may determine the tissue impedance by dividing the output of the second voltage sensing circuit 524 coupled across the terminals labeled ENERGY2/RETURN by the output of the current sensing circuit 514 disposed in series with the RETURN leg of the secondary side of the power transformer 508 as shown in FIG. 8. Initially, the end effector 125 of the surgical instrument 108 is closed 6302 on the tissue and the end effector 125 is activated with RF energy from the generator 500. A technique for controlling the RF energy being delivered from the generator 500 to the tissue is applied 6304 to effect a tissue seal using the RF energy. This technique may comprise selecting and applying composite load curves (CLC) tables by the processor 502 of the generator 500, as described in connection with FIG. 64 hereinbelow. The processor 502 compares 6306 the tissue impedance to a threshold value to determine if the tissue impedance has reached the termination impedance at which time the generator 500 can switch from RF energy for coagulating or sealing tissue to ultrasonic energy for cutting tissue. Until the termination impedance is reached, the processor 502 proceeds along the NO branch to and signals the waveform generator 540 or amplifier 506 to continue delivering 6304 RF energy to the end effector 125. When the termination impedance is reached, the processor 502 proceeds along the YES branch and signals the waveform generator 504 or amplifier 506 to stop delivering RF energy (ENERGY2/RETURN) and the switch 6308 to delivering ultrasonic energy (ENERGY1/RETURN). Upon completing the tissue cut utilizing ultrasonic energy, the tissue is released 6310 from the end effector 125.

FIGS. 91A and 91B illustrate example graphs of the energy, both RF and ultrasonic, that is delivered to an end effector 125 of a surgical instrument 108 from a generator 500. The technique as described herein can be used to control the RF and ultrasonic energy to automatically switch from RF to ultrasonic energy to perform tissue cutting. A combined RF and ultrasonic surgical instrument 108 would then use a technique graphically depicted in FIGS. 91A and 91B to deliver and control RF energy to the electrodes in the end effector 125. At the end of the termination pulses 6406 (FIG. 91A), the generator 500 can automatically switch over to the ultrasonic mode to perform the tissue cutting.

In particular, FIG. 91A is a graphical depiction 6400 of a generator RF power 6402 function and RF tissue impedance function 6404 represented as functions of time. The RF power function 6402 is delivered from a generator 500 to an end effector 125 of a surgical instrument 108. Power (Joules) is shown along the left vertical axis, tissue impedance (Ohms) is shown along the right vertical axis, and time (Seconds) is shown along the horizontal axis. FIG. 91B is a graphical depiction 6450 of a RF voltage function 6452 and a RF current function 6454 represented as functions of time. The RF voltage and current functions 6452, 6454 coincide with the RF power and impedance functions 6402, 6404 delivered from the generator 500 to the electrodes in the end effector 125 of the surgical instrument 108. RF voltage (V) is shown along the left vertical axis, RF current (mA) is shown along the right vertical axis, and time (Seconds) is shown along the horizontal axis. Although the graphical depictions 6400, 6450 of the RF power function 6402 and the RF tissue impedance function 6404 and the RF voltage and RF current functions 6452, 6454 are shown in two separate graphs, it will be appreciated that all four functions 6402, 6404, 6452, 6454 occur simultaneously in response to the tissue impedance and techniques executed by the control circuits of the generator 500.

The graphical depiction 6400 of the RF power function 6402, the RF tissue impedance function 6404, the RF voltage function 6452, and the RF current function 6454 are divided into three separate modes. In Mode 1, the generator 500 delivers the RF power function 6402 to the electrodes in contact with the tissue clamped between the clamp jaw 145 and the ultrasonic blade 149 of the end effector 125. In Mode 1, the tissue impedance is low and demands high RF current 6454 from the generator 500. Thus, as the RF current 6452 is pulsed the RF voltage 6454 drops below its nominal output level. While the RF power 6402 is delivered to the tissue, the generator 500 enters Mode 2 where the control circuit manages the RF power 6402 delivered to the tissue to effect a proper seal. In one aspect, during Mode 2, the process includes selecting and applying CLC tables by the processor 502 of the generator 500, as described in connection with FIG. 64 hereinbelow. As the RF power function 6402 is applied to the tissue in Modes 1 and 2, the tissue begins to seal and moisture is evaporated for the tissue due to the heat generated in the process causing the tissue impedance to increase. This is known as the “bathtub” zone, as previously described in connection with the tissue impedance function 6200 in FIG. 89. Back to FIG. 91B, the generator 500 enters Mode 3 when the tissue impedance reaches a termination impedance 6406 of the RF tissue impedance function 6404. In Mode 3, the processor 502 signals the waveform generator 504 to employ RF energy to measure the tissue impedance and to use ultrasonic energy to the ultrasonic blade 149 to cut the tissue. Non-therapeutic RF power function 6402 may be applied to the tissue to measure the tissue impedance during the ultrasonic cutting phase in Mode 3.

FIG. 91C is a graphical depiction 6475 of the power function 6402, impedance function 6404, voltage function 6452, and current function 6453 as a function of time delivered from a generator to an end effector of a surgical instrument as shown in FIGS. 91A and 91B.

Simultaneous Control Techniques for Combination Ultrasonic/RF Surgical Instrument

In one aspect, the present disclosure provides a technique for controlling the power output from a generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8). The power delivered to an end effector of a surgical instrument can include simultaneous activation of RF and ultrasonic energy modalities to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for simultaneously activating RF and ultrasonic energy modalities will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The following description provides techniques for simultaneous activation of RF and ultrasonic energy modalities to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the simultaneous application of different energy modalities will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

There are many benefits to a surgical instrument 108 that is capable of delivering both RF and ultrasonic energy. By having both modalities in one instrument 108, the instrument 108 is able to create stronger seals and also cut without the need for a separate knife. The following disclosure provides multiple simultaneous energy delivery techniques that could be used for sealing various vessels.

In general, the present disclosure provides a surgical instrument 108 and generator 500 capable of simultaneous activation of both RF and ultrasonic energy modalities. The simultaneous activation of both RF and ultrasonic energy modalities may be implemented utilizing a single generator capable of delivering both energy modalities from two or more ports, two separate generators, or a single port generator 500 capable of delivering both RF and ultrasonic energy modalities via a single port. Multiple configurations of the simultaneous techniques are disclosed. In one aspect, a technique utilizes CLC tables to implement an RF sealing technique while the ultrasonic energy is activated at a constant power level. Accordingly, the RF CLC tables are activated at the same time that ultrasonic energy is delivered. In one aspect, the technique selects and applies the CLC tables process according to FIG. 81.

During a seal only mode, the activation of power for both RF and ultrasonic energies are terminated at the point at which the RF termination impedance is reached, therefore, preventing the risk of inadvertently cutting through the tissue. One advantage of simultaneous activation of RF and ultrasonic energy modalities is that the ultrasonic energy heats up the ultrasonic blade 149 and helps to create a reduction in the difference in thermal mass between the ultrasonic blade 149 and the electrode.

In particular, FIG. 92 is a logic flow diagram 6500 of one aspect of a process of applying simultaneous activation of different energy modalities to tissue. As described herein, the logic flow diagram 6500 may be implemented in the generator 500, the surgical instrument 108, or a combination thereof. Wth reference now to the logic flow diagram 6500, tissue is clamped between the clamp arm 145 and the ultrasonic blade 149 of the end effector 125 of the surgical instrument 108 and then the generator 500 applies the simultaneous energy modalities. The RF energy delivery process 6502 is shown on the left side of the logic flow diagram 6500 and the ultrasonic energy delivery process 6512 is shown on the right. Once the tissue is clamped between the clamp jaw 145 and the ultrasonic blade 149, the processor 502 signals the waveform generator 504 to activate 6504 the RF energy and to activate 6514 the ultrasonic energy at a constant power level. Once the RF energy is activated 6504 the processor 502 signals the waveform generator 504 to deliver 6506 RF sealing techniques and to maintain 6516 the ultrasonic energy at a constant power level activation. In one aspect, the RF sealing techniques applied by the generator 500 involve selecting and applying the CLC tables according to the process described in FIG. 81. Referring back to FIG. 92, during the application 6506 of the RF sealing techniques, the processor 502 monitors the tissue impedance and determines when the termination impedance is reached. When the termination impedance is reached 6508, feedback is signaled 6518 to the processor 502 to terminate the ultrasonic power delivery. Subsequently, the processor 502 signals the waveform generator 504 to terminate 6510 the RF power and to terminate 6520 the ultrasonic power. As previously discussed, the processor 502 measures the RF tissue impedance by dividing the output of the second voltage sensing circuit 524 by the output of the current sensing circuit 514.

FIG. 93 is a graphical depiction 6600 of an RF tissue impedance function 6602 represented as RF tissue impedance (Ohms) as a function of time (Sec) in connection with the logic flow diagram 6500 of FIG. 92 to illustrate first and second termination impedances. As previously described, one advantage of simultaneous activation of RF and ultrasonic energy modalities is that the ultrasonic energy heats up the blade and helps to create a reduction in the difference in thermal mass between the blade and the electrode. In the graphical depiction 6600 of FIG. 93, the horizontal axis is time (ms) and the vertical axis is RF tissue impedance (Ohms). The first portion 6604 of the RF tissue impedance function 6602 coincides with the application of the RF energy sealing process described in connection with FIG. 64 and the constant ultrasonic power. The tissue impedance is monitored during the tissue sealing process utilizing the RF energy. When the tissue impedance reaches a first termination impedance 6606, the ultrasonic power is terminated and when the tissue impedance reaches a second termination impedance 6608 the RF power is terminated to avoid cutting through the sealed tissue.

FIG. 94 illustrates an example of the quality of a seal 6702 made in a vessel 6700 utilizing simultaneous activation of RF and ultrasonic energy modalities as described in connection with FIGS. 92 and 93. The main advantage of simultaneous activation of RF and ultrasonic energy modalities is that the ultrasonic energy heats up the ultrasonic blade 149 and helps to create a reduction in the difference in thermal mass between the ultrasonic blade 149 and the electrode in the clamp arm 145. During a non-simultaneous activation seal cycle utilizing both RF and ultrasonic modalities, a challenge is posed to create a strong seal with varying thermal masses on either side of the end effector 125 jaw. The boxplots shown in FIGS. 95 and 96 below demonstrate the tissue effect advantages mentioned above (simultaneously heating the ultrasonic blade 149 and electrode) of activating a simultaneous energy modality technique.

FIG. 95 is a boxplot graphic 6800 comparison of the burst pressure of a carotid artery seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94. Energy modality is shown along the horizontal axis and burst pressure (mmHg) of the two carotid artery seals represented by first and second boxplots 6802, 6804 is shown along the vertical axis. Along the horizontal axis, the first boxplot 6802 represents a carotid artery seal made utilizing simultaneous RF/ultrasonic energy and the second boxplot 6804 represents a carotid artery seal made utilizing RF energy only. The first and second boxplots 6802, 6804 demonstrate the tissue effect advantages provided by the simultaneous application of RF/ultrasonic energy modality as depicted by the logic flow diagram 6500 of FIG. 92 where simultaneously heating the ultrasonic blade 149 and electrode provides the high quality tissue seal 6702 shown in FIG. 94.

FIG. 96 is a boxplot graphic 6900 comparison of the burst pressure of a carotid artery bundle seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94. Energy modality is shown along the horizontal axis and burst pressure (mmHg) of the two carotid artery bundle seals represented by first and second boxplots 6902, 6904 is shown along the vertical axis. Along the horizontal axis, the first boxplot 6902 representing a carotid artery bundle seal made utilizing simultaneous RF/ultrasonic energy and the second boxplot 6904 represents a carotid artery bundle seal made utilizing RF energy only. The first and second boxplots 6902, 6904 demonstrate the tissue effect advantages provided by the simultaneous application of RF/ultrasonic energy modality as depicted by the logic flow diagram 6500 of FIG. 92 where simultaneously heating the ultrasonic blade 149 and electrode provides the high quality tissue seal 6702 shown in FIG. 94.

FIG. 97 is a boxplot graphic 7000 comparison of the burst pressure of a thyrocervical artery seal made utilizing: (1) simultaneous application of RF and ultrasonic energy and (2) application of RF energy only as described in connection with FIGS. 92-94. Energy modality is shown along the horizontal axis and burst pressure (mmHg) of the two thyrocervical artery seals represented by first and second boxplots 7002, 7004 is shown along the vertical axis. Along the horizontal axis, the first boxplot 7002 represents a thyrocervical artery seal made utilizing simultaneous RF/ultrasonic energy and the second boxplot 7004 represents a thyrocervical artery seal made utilizing RF energy only. The first and second boxplots 7002, 7004 demonstrate the tissue effect advantages provided by the simultaneous application of RF/ultrasonic energy modality as depicted by the logic flow diagram 6500 of FIG. 92 where simultaneously heating the ultrasonic blade 149 and electrode provides the high quality tissue seal 6702 shown in FIG. 94.

There are several factors that can drive the simultaneous RF/ultrasonic energy application technique. Ultrasonic power level is a factor if a “seal only” configuration is desired. For example, a lower ultrasonic power level may be selected as not to cut through the tissue. Data suggests that the higher the ultrasonic power level, the greater the seal results as shown and described below in connection with FIG. 98. In particular, FIG. 98 is a boxplot graphic 7100 comparison of the burst pressure of a carotid artery bundle seal made utilizing simultaneous application of: (1) RF and lower ultrasonic energy and (2) RF energy and higher ultrasonic energy as described in connection with FIGS. 92-94. Ultrasonic power level is shown along the horizontal axis and burst pressure (mmHg) of the two carotid artery bundle seals represented by first and second boxplots 7102, 7104 is shown along the vertical axis. Along the horizontal axis, the first boxplot 7102 represents a carotid artery bundle seal made utilizing simultaneous RF energy and lower ultrasonic energy and the second boxplot 7104 represents a carotid artery bundle seal made utilizing RF energy and lower ultrasonic energy relative to the first boxplot 7102. The first and second boxplots 7102, 7104 demonstrate that the higher the ultrasonic power level, the greater the seal.

If a “seal and cut” configuration is desired, a higher ultrasonic power level may be selected as an option to seal and cut tissue more efficiently with great tissue effects. Additionally, ultrasonic power level can also be altered during the seal/transection cycle based on the RF tissue impedance feedback. During a seal and cut cycle, the RF tissue impedance can be monitored and ultrasonic power delivered based on RF feedback impedance. There are different points during a seal in which impedance readings are useful including, for example, termination Impedance and power pulse impedance.

In regard to the termination impedance, one of which is the termination impedance which occurs as the impedance rises out of the sealing zone 6604 at a steady rate, as shown in FIG. 93. In particular, FIG. 99 is a boxplot graphic 7200 comparison of the burst pressure of a carotid artery bundle seal made utilizing simultaneous application of RF and ultrasonic energy at different termination impedances as described in connection with FIGS. 92-94. Termination impedance (Ohms) is shown along the horizontal axis and burst pressure (mmHg) of the two carotid artery bundle seals represented by first and second boxplots 7202, 7204 is shown along the vertical axis. Along the horizontal axis, the first boxplot 7202 represents a carotid artery bundle seal made utilizing simultaneous application of RF energy and ultrasonic energy terminated at a termination impedance of 1000 Ohms and the second boxplot 7204 represents a carotid artery bundle seal made utilizing simultaneous application of RF energy and ultrasonic energy terminated at a termination impedance of 2000 Ohms. The first and second boxplots 7202, 7204 demonstrate that the higher the termination impedance, the greater the seal. Thus, termination impedance is a statistical factor in the bundle tissue model for burst pressure as it yielded greater burst pressure results.

The power pulse impedance threshold is another point at which the sealing process could be optimized. This is the point at which the power pulse of the CLC tables delivers the most energy into the tissue. It monitors the point at which the impedance threshold is reached to know when the tissue has reached the state to begin the termination pulses. Changing the impedance value of the power pulse (lower value) can enable faster seal times with the same great burst pressure results.

Modulation Techniques for Ultrasonic Energy in Seal Only and Seal and Cut Modes

In one aspect, the present disclosure provides techniques for modulating ultrasonic energy in seal only mode and seal and cut mode. The power output from a generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), is controlled to modulate ultrasonic energy in seal only mode and seal and cut mode. The ultrasonic energy delivered to an end effector of a surgical instrument can be modulated to provide “seal only” mode or “seal and cut” mode to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for modulating ultrasonic energy in seal only mode and seal and cut mode will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The following description provides techniques for modulating ultrasonic energy in seal only and seal and cut modes to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the simultaneous application of different energy modalities will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

In general, a surgical instrument 108 configured with a “seal only” mode and a “seal and cut” mode provide the surgeons the option of sealing or sealing and cutting tissue based on their intended surgical task. In one aspect, the surgical instrument 108 is configured to utilize both RF and ultrasonic technology in combination to achieve this task. In one aspect, in a “seal only” mode, the generator 500 is configured to determine when a cut is complete to eliminate a partial transection 7304 as shown in FIG. 100 below. An example of a vessel with a quality vessel seal made utilizing simultaneous application of RF and ultrasonic energy is shown FIG. 99. In particular, FIG. 100 is an example of a vessel 7360 with a partial seal 7302 made utilizing simultaneous application of RF and ultrasonic energy and a partial transection 7304 made utilizing ultrasonic energy.

Accordingly, it is desirable to provide “seal only” and “seal and cut” techniques utilizing RF and ultrasonic energy modalities to optimize the quality of seal and a seal and cut operation. In one aspect, a “seal only” technique may be applied as graphically depicted in FIG. 101. The seal only technique delivers simultaneous energy of ultrasonic and RF for the duration of the seal. The seal only technique can be optimized by modulating the ultrasonic energy delivered based on the RF tissue impedance.

In particular, FIG. 101 is a graphical depiction 7400 of an RF tissue impedance function 7402 represented as RF tissue impedance (Ohms) as a function of time (Sec) and an ultrasonic current function 7404 represented as ultrasonic current (mA) as a function of time (Sec) during a “seal only” modality. Time (Sec) is shown along the horizontal axis, impedance (Ohms) is shown along the left vertical axis, and ultrasonic current (mA) is shown along the right vertical axis. The “seal only” modality is achieved in three separate stages. During a first stage 7406, only RF energy is delivered to the electrodes and the ultrasonic current function 7404 is zero. During the first stage 7406, the impedance is slightly above zero such that power can be delivered to the tissue. At the end of the first stage 7406 and marking the beginning of the second stage 7408, the ultrasonic energy is delivered to the ultrasonic blade 149 in conjunction with the RF energy. During the second stage 7408, the ultrasonic current 7414 remains constant at −200 mA and the impedance begins to slowly increase as the tissue dries during the sealing process. Once the inflection point 7412 of the impedance function 7402 is reached, at the end of the second stage 7408 marking the beginning of the third stage 7410, the impedance starts to rapidly increase. The impedance is fed back to the generator 500 and when the impedance is equal to or greater than the inflection point 7412 impedance, the generator 500 decrements the ultrasonic current to reduce the amount of ultrasonic energy applied to the tissue to avoid cutting the tissue and achieve the seal only modality. During the third stage 7410, the ultrasonic current is decremented by equal steps 7416, as shown in FIG. 101, until the seal is complete, but without cutting the tissue. In other aspects, the ultrasonic current may be decremented by variable and non-equal steps 7416. In one aspect the decrement value is −50 mA, and thus the first decremented current value is −150 mA. When the impedance reaches a termination impedance, both the RF and ultrasonic power are turned off.

FIG. 102 is logic flow diagram 7500 of one aspect of a technique for simultaneous activation of RF and ultrasonic energy and modulating the ultrasonic energy to achieve a seal only process. As described herein, the logic flow diagram 7500 may be implemented in the generator 500, the surgical instrument 108, or a combination thereof. Wth reference to the graphical depiction 7400 of FIG. 101 and in accordance with the logic flow diagram 7500 of FIG. 102, the processor 502 signals the waveform generator 504 to deliver 7502 RF energy to the end effector 125 (e.g., to the electrode) for a first period during the first stage 7406 of the seal only process. At the end of the first period, the processor 502 signals the waveform generator 504 to deliver 7504 ultrasonic energy to the end effector 125 (e.g., to the ultrasonic blade 149) for a second period during the second stage 7408 of the seal only process. The processor 502 monitors 7506 the RF tissue impedance and compares 7508 the RF tissue impedance to a predetermined impedance corresponding to the inflection point 7412 impedance of the impedance function 7402 as shown in FIG. 101. If the RF tissue impedance is less than the predetermined inflection point 7412 impedance (“inflection impedance”), near the end of the sealing stage where the impedance begins to rapidly rise, the processor 502 proceeds along the NO branch and continues to monitor 7506 the RF tissue impedance while RF energy and constant ultrasonic energy is delivered 7502, 7504 to the end effector 125 during the second stage 7408 of the seal only process. As previously discussed, the processor 502 measures the RF tissue impedance by dividing the output of the second voltage sensing circuit 524 by the output of the current sensing circuit 514.

When the RF tissue impedance is equal to or greater than the inflection impedance, the process proceeds along the YES branch and the processor 502 signals the waveform generator 504 to reduce 7510 the ultrasonic energy from a first power level to a second power level by a predetermined decrement (˜50 mA, or any suitable or desired value). The ultrasonic energy may be reduced by a discrete reduction of a numerical quantity or may be reduced by a continuous quantity. In one aspect, the ˜200 mA ultrasonic current delivered during the second stage 7408 is decreased by a ˜50 mA step to ˜150 mA, to minimize the risk of partially transecting or cutting the vessel and achieve the seal only modality. The processor 502 compares 7512 the RF tissue impedance to a predetermined termination impedance. If the RF tissue impedance is less than the termination impedance, the processor 502 proceeds along the NO branch and the ultrasonic current function 7404 is reduced 7510 by the predetermined step, which can be done in equal or variable steps. When the RF tissue impedance is equal to or greater than the termination impedance, the processor 502 proceeds along the YES branch and the generator 500 terminates 7514 both the RF and ultrasonic energy. The modulated ultrasonic current function 7404 shown in FIG. 101 enables the achievement of a “seal only” modality without the risk of a partial transection. The technique can be store as a logic function or series of computer executable instructions in a look-up table in memory, such as an EEPROM located on the surgical instrument 108 or the generator 500.

In particular, FIG. 103 is a graphical depiction 7600 of an RF tissue impedance function 7602 represented as RF tissue impedance (Ohms) as a function of time (Sec) and an ultrasonic current function 7404 represented as ultrasonic current (mA) as a function of time (Sec) during a “seal and cut” modality. Time (Sec) is shown along the horizontal axis, impedance (Ohms) is shown along the left vertical axis, and ultrasonic current (mA) is shown along the right vertical axis. The “seal and cut only” modality is achieved in three separate stages. During a first stage 7606, only RF energy is delivered to the electrodes and the ultrasonic current function 7604 is zero. During the first stage 7606, the impedance is slightly above zero such that power can be delivered to the tissue. At the end of the first stage 7606 and marking the beginning of the second stage 7608, the ultrasonic energy is delivered to the ultrasonic blade 149 in conjunction with the RF energy. During the second stage 7608, the ultrasonic current 7614 remains constant at ˜200 mA and the impedance begins to slowly increase as the tissue dries during the sealing process. Once the inflection point 7612 of the impedance function 7602 is reached, at the end of the second stage 7608 marking the beginning of the third stage 7610, the impedance starts to rapidly increase. The impedance is fed back to the generator 500 and when the impedance is equal to or greater than the inflection point 7612 impedance, the generator 500 increments the ultrasonic current to increase the amount of ultrasonic energy applied to the tissue to achieve the seal and cut modality. During the third stage 7610, the ultrasonic current is incremented in equal steps 7616, as shown in FIG. 103, until the seal and cut is achieved. In other aspects, the ultrasonic current may be incremented by variable and non-equal steps. In one aspect the increment step 7616 value is ˜50 mA, and thus the first incremented current value is ˜150 mA. When the impedance reaches a termination impedance indicating that the cut is complete, both the RF and ultrasonic power are turned off.

FIG. 104 is a logic flow diagram 7700 of one aspect of a technique for simultaneous activation of RF and ultrasonic energy and modulating the ultrasonic energy to achieve a seal and cut process. As described herein, the logic flow diagram 7700 may be implemented in the generator 500, the surgical instrument 108, or a combination thereof. Wth reference to the graphical depiction 7600 of FIG. 103 and in accordance with the logic flow diagram 7700 of FIG. 104, the processor 502 signals the waveform generator 504 to deliver 7702 RF energy to the end effector 125 (e.g., to the electrode) for a first period during the first stage 7606 of the seal and cut process. At the end of the first period, the processor 502 signals the waveform generator 504 to deliver 7704 ultrasonic energy to the end effector 125 (e.g., the ultrasonic blade 149) for a second period during the second stage 7608 of the seal and cut process. The processor 502 monitors 7706 the RF tissue impedance during a sealing portion of the seal and cut process. The processor 502 compares 7708 the RF tissue impedance to a predetermined impedance corresponding to the inflection point 7612 of the impedance function 7602. If the RF tissue impedance is less than the predetermined inflection point 7612 impedance (“inflection impedance”), near the end of the sealing stage where the impedance begins to rapidly rise, the processor 502 proceeds along the NO branch and continues to monitor 7706 the RF tissue impedance while RF energy and constant ultrasonic energy is delivered 7702, 7704 to the end effector 125 during the second stage 7408 of the seal and cut process. As previously discussed, the processor 502 measures the RF tissue impedance by dividing the output of the second voltage sensing circuit 524 by the output of the current sensing circuit 514.

When the RF tissue impedance is equal to or greater than the inflection impedance, the processor 502 proceeds along the YES branch and signals the waveform generator 504 to increase 7710 the ultrasonic energy from a first power level to a second power level by a predetermined decrement (˜75 mA, or any suitable or desired value). The ultrasonic energy may be increased by a discrete reduction of a numerical quantity or may be increased by a continuous quantity. In one aspect, the ˜200 mA ultrasonic current is increased to ˜275 mA by a ˜75 mA step to achieve the seal and cut modality. The processor 502 compares 7712 the RF tissue impedance to a predetermined termination impedance. If the RF tissue impedance is less than the termination impedance, the processor 502 proceeds along the NO branch and the ultrasonic current function 7604 is increased 7710 by the predetermined step, which can be done in equal or variable steps. When the RF tissue impedance is equal to or greater than the termination impedance, the process proceeds along the YES branch and the generator 500 terminates 7714 both the RF and ultrasonic energy once the seal and cut has been achieved. The modulated ultrasonic current function 7604 shown in FIG. 103 enables the achievement of a “seal and cut” modality. The technique can be store as a logic function or series of computer executable instructions in a look-up table in memory, such as an EEPROM located on the surgical instrument 108 or the generator 500.

Techniques for Reducing Displacement of Ultrasonic Blade as a Function of RF Tissue Impedance

In one aspect, the present disclosure provides techniques to reduce ultrasonic blade displacement as a function of RF tissue impedance for RF/Ultrasonic combination surgical instruments. The power output from a generator, such as the generators 102, 200, 300, 400, 500 (FIGS. 1-3 and 4-8), is delivered to an end effector of a surgical instrument and can be controlled to reduce the displacement of an ultrasonic blade as a function of RF tissue impedance to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the techniques for reducing ultrasonic blade displacement as a function of RF tissue impedance will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

The following description provides techniques for reducing the displacement of an ultrasonic blade as a function of RF tissue impedance to treat the tissue clamped between a clamp jaw and an ultrasonic blade of the end effector of the surgical instrument. For conciseness and clarity of disclosure, the simultaneous application of different energy modalities will be described with reference to the surgical instrument 108 of FIG. 2 coupled to the generator 500 of FIG. 8, although it will be appreciated that other configurations of instruments, generators, and end effectors described herein may be readily substituted without departing from the scope of the present disclosure.

In general, it is desirable to reduce the displacement of the ultrasonic blade 149 as a function of RF tissue impedance. Reduction of the ultrasonic blade 149 displacement can prevent prematurely cutting the tissue clamped between the clamp jaw 145 and the ultrasonic blade 149 of the end effector 125 if cutting tissue is not desired. In order to decay the displacement of the ultrasonic blade 149, a rise in RF tissue impedance can be used as feedback to the generator 500 as is well known that RF tissue impedance indicates the state of the tissue. For example, tissue with low impedance (i.e., in the first phase of the tissue sealing process) at current operating pressures indicates that the tissue has not yet been cut because the low impedances indicate the presence of tissue between the clamp jaw 145 and the ultrasonic blade 149 of the end effector 125. In general, there has been a reluctance to use high ultrasonic energy while the tissue is in the first phase of sealing for fear of cutting the tissue prematurely. Nevertheless, high ultrasonic energy is desirable in this phase to facilitate energy delivery to tissue when the RF tissue impedance is too low to drive electrical power into large bites of tissue.

A simple mathematical relationship between RF tissue impedance (Z) and ultrasonic blade displacement controlled by the current I_(h) flowing through the ultrasonic transducer can be employed to decay the displacement of the ultrasonic blade to zero or similar low value to prevent cutting tissue. A number of mathematical mappings exist to appropriately reduce I_(h) as a function of Z such as neural networks, fuzzy logic, polynomials, radial basis functions, Fourier series, and the like, because many functions and series have been proven to map any relationship when a sufficiently high enough order is used. However, only a few functions exist that have a small number of adjustable gains that are intuitive to enable optimization. An intuitive functional mapping is represented in Equation 9 below:

$\begin{matrix} {I_{h} = \left\{ {\begin{matrix} I_{\max} \\ \frac{I_{\max}\left( {Z^{- n} - Z_{\max}^{- n}} \right)}{\left( {Z_{\min}^{- n} - Z_{\max}^{- n}} \right)} \\ 0 \end{matrix}\begin{matrix} \forall \\ \forall \\ \forall \end{matrix}\begin{matrix} {\mspace{76mu} {Z < Z_{\min}}} \\ {Z_{\min} < Z < Z_{\max}} \\ {\mspace{76mu} {Z > Z_{\max}}} \end{matrix}} \right.} & {{Equation}\mspace{14mu} 9} \end{matrix}$

Where I_(max) is the maximum current the ultrasonic blade can tolerate, Z_(min) is the threshold impedance that dictates when the tissue has exited the “first phase,” Z_(max) is the impedance at which it is desired to have I_(h)=0 Amps, and the exponent n dictates the rate of decay of the tissue. Both the max and min impedance values can be dynamically updated as a function of the initial Z of the tissue during energy onset. A plot of Equation 1 with Z_(max)=500 Ohm, Z_(min)=50 Ohm, and I_(max)=200 mA for various n values is presented in FIG. 105.

In particular, FIG. 105A is a graphical depiction 7800 of an ultrasonic current functions represented as ultrasonic current I_(h) (Amperes) delivered to the ultrasonic transducer as a function of RF tissue impedance Z (Ohms) for various n values. The horizontal axis is RF tissue impedance Z (Ohms) and the vertical axis is ultrasonic current I_(h) (Amperes). The first ultrasonic current function 7802 has n=2. The second ultrasonic current function 7804 has n=1. The third ultrasonic current function 7806 has n=−0.25. The fourth ultrasonic current function 7808 has n=−1. The fifth ultrasonic current function 7810 has n=−3. The sixth ultrasonic current function 7812 has n=−10.

Additionally, FIG. 105B is a graphical depiction 7800′ of another set of ultrasonic current functions represented as ultrasonic current I_(h) (Amperes) delivered to the ultrasonic transducer as a function of RF tissue impedance Z (Ohms) for various n values. The horizontal axis is RF tissue impedance Z (Ohms) and the vertical axis is ultrasonic current In (Amperes). The first ultrasonic current function 7802′ has n=0.03. The second ultrasonic current function 7804′ has n=0.04. The third ultrasonic current function 7806′ has n=0.06. The fourth ultrasonic current function 7808′ has n=0.1.

FIG. 106 is a graphical depiction 7900 of multiple ultrasonic functions represented as functions of time. In particular, FIG. 106 is a graphical depiction 7900 of voltage 7902 (V) as a function of time (Sec), current 7904 (A) as a function of time (Sec), power 7906 (W) as a function of time (Sec), and frequency (kHz) as a function of time (Sec), where voltage (V) and current (A) are shown along the left vertical axis, power (W) and impedance (Ohm) are shown along the right vertical axis, and time (Sec) is shown along the horizontal axis.

FIG. 107 is a graphical depiction 8000 of constant RF power that was inputted into Equation 1 with RF energy terminated at 500 Ohm terminal impedance. In particular, FIG. 107 is a graphical depiction 8000 of voltage 8002 (V) as a function of time (Sec), current 8004 (A) as a function of time (Sec), power 8006 (W) as a function of time (Sec), and impedance (Ohms) as a function of time (Sec), where voltage (V) and current (A) are shown along the left vertical axis, power (W) and impedance (Ohm) are shown along the right vertical axis, and time (Sec) is shown along the horizontal axis.

Although the surgical system 100 is independent of the RF technique being applied, for clarity of illustration, a constant RF power was delivered to tissue and the ultrasonic current into the ultrasonic transducer was reduced accordingly as shown in FIGS. 106 and 107. This technique achieves a tissue seal without cutting the tissue. In FIG. 107, the RF termination impedance was set to 500 Ohms and n=−1. The RF power delivered (with low risk of cutting tissue) does not need to terminate at the same time that the ultrasonic power is terminated. Post phase one, the RF power heating of tissue improves sealing and can continue once ultrasonic power has been shut off. For a given jaw pressure and geometry, a surface response design of experiment can be performed to optimize the parameter values.

While various details have been set forth in the foregoing description, it will be appreciated that the various aspects of the surgical system with user adaptable techniques based on tissue type may be practiced without these specific details. For example, for conciseness and clarity selected aspects have been shown in block diagram form rather than in detail. Some portions of the detailed descriptions provided herein may be presented in terms of instructions that operate on data that is stored in a computer memory. Such descriptions and representations are used by those skilled in the art to describe and convey the substance of their work to others skilled in the art. In general, a technique refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may, though need not necessarily, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.

Unless specifically stated otherwise as apparent from the foregoing discussion, it is appreciated that, throughout the foregoing description, discussions using terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

It is worthy to note that any reference to “one aspect,” “an aspect,” “one form,” or “an form” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, appearances of the phrases “in one aspect,” “in an aspect,” “in one form,” or “in an form” in various places throughout the specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more aspects.

Some aspects may be described using the expression “coupled” and “connected” along with their derivatives. It should be understood that these terms are not intended as synonyms for each other. For example, some aspects may be described using the term “connected” to indicate that two or more elements are in direct physical or electrical contact with each other. In another example, some aspects may be described using the term “coupled” to indicate that two or more elements are in direct physical or electrical contact. The term “coupled,” however, also may mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other.

Although various forms have been described herein, many modifications, variations, substitutions, changes, and equivalents to those forms may be implemented and will occur to those skilled in the art. Also, where materials are disclosed for certain components, other materials may be used. It is therefore to be understood that the foregoing description and the appended claims are intended to cover all such modifications and variations as falling within the scope of the disclosed forms. The following claims are intended to cover all such modification and variations.

In a general sense, those skilled in the art will recognize that the various aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). Those having skill in the art will recognize that the subject matter described herein may be implemented in an analog or digital fashion or some combination thereof.

The foregoing detailed description has set forth various forms of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one form, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, those skilled in the art will recognize that some aspects of the forms disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative form of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.), etc.).

All of the above-mentioned U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, non-patent publications referred to in this specification and/or listed in any Application Data Sheet, or any other disclosure material are incorporated herein by reference, to the extent not inconsistent herewith. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

One skilled in the art will recognize that the herein described components (e.g., operations), devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components (e.g., operations), devices, and objects should not be taken limiting.

Wth respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity.

The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely example, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated also can be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated also can be viewed as being “operably couplable,” to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wirelessly interacting components, and/or logically interacting, and/or logically interactable components.

In some instances, one or more components may be referred to herein as “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Those skilled in the art will recognize that “configured to” can generally encompass active-state components and/or inactive-state components and/or standby-state components, unless context requires otherwise.

While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.”

Wth respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.

Although various forms have been described herein, many modifications, variations, substitutions, changes, and equivalents to those forms may be implemented and will occur to those skilled in the art. Also, where materials are disclosed for certain components, other materials may be used. It is therefore to be understood that the foregoing description and the appended claims are intended to cover all such modifications and variations as falling within the scope of the disclosed forms. The following claims are intended to cover all such modification and variations.

In summary, numerous benefits have been described which result from employing the concepts described herein. The foregoing description of the one or more forms has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The one or more forms were chosen and described in order to illustrate principles and practical application to thereby enable one of ordinary skill in the art to utilize the various forms and with various modifications as are suited to the particular use contemplated. It is intended that the claims submitted herewith define the overall scope. 

1.-22. (canceled)
 23. A method comprising: applying a force to tissue using an end effector of a surgical instrument; measuring, by a processor, the force applied to the tissue; comparing, by the processor, the measured force to a threshold minimum force value; determining, by the processor, that the measured force satisfies the threshold minimum force value; measuring, by the processor, a value of power by the end effector when the end effector applies the force to the tissue; computing, by the processor, a coefficient of determination value using the value of power and the measured force; determining, by the processor, a coefficient of friction of the tissue using the coefficient of determination value; determining, by the processor, a type of tissue by comparing the determined coefficient of friction to a database relating stored coefficients of friction to predetermined types of tissue; and selecting, by the processor, a power delivery profile for delivering energy from a generator to the end effector that is suitable for performing a surgical operation on the determined type of tissue.
 24. The method of claim 23, wherein determining the coefficient of friction of the tissue comprises: applying and measuring a plurality of forces, each at different values, to the tissue using the end effector; measuring, by the processor, for each of the plurality of forces, a respective value of power; and computing, by the processor, for each pair of the plurality of forces and respective values of power, a slope value using said pair of force and respective value of power;
 25. The method of claim 24, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a respective coefficient of determination for each of the slope values.
 26. The method of claim 25, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a best fit slope value among each of the slope values that corresponds to the highest coefficient of determination among the respective coefficients of determination.
 27. The method of claim 26, wherein determining the coefficient of friction of the tissue further comprises: determining that the highest coefficient of determination satisfies a predetermined threshold; and based on the determination that the predetermined threshold is satisfied, computing the coefficient of friction using the best fit slope value.
 28. The method of claim 23, further comprising dynamically changing the power delivery profile based on determining a change in the tissue coefficient of friction of the tissue.
 29. The method of claim 23, further comprising entering a learning mode to improve accuracy of determining the coefficient of friction.
 30. A method comprising: applying a force to tissue using an end effector of a surgical instrument; measuring, by a processor, the force applied to the tissue; comparing, by the processor, the measured force to a threshold minimum force value; determining, by the processor, that the measured force satisfies the threshold minimum force value; measuring, by the processor, a value of power by the end effector when the end effector applies the force to the tissue; computing, by the processor, a coefficient of determination value using the value of power and the measured force; determining, by the processor, a coefficient of friction of the tissue using the coefficient of determination value; determining, by the processor, a type of tissue by comparing the determined coefficient of friction to a database relating stored coefficients of friction to predetermined types of tissue, the predetermined types of tissue including porcine carotid with a coefficient of friction of 0.30, porcine carotid with a coefficient of friction of 0.35, porcine bowel with a coefficient of friction of 0.19, and dry chamois with a coefficient of friction of 0.75; and selecting, by the processor, a power delivery profile for delivering energy from a generator to the end effector that is suitable for performing a surgical operation on the determined type of tissue.
 31. The method of claim 30, wherein determining the coefficient of friction of the tissue comprises: applying and measuring a plurality of forces, each at different values, to the tissue using the end effector; measuring, by the processor, for each of the plurality of forces, a respective value of power; and computing, by the processor, for each pair of the plurality of forces and respective values of power, a slope value using said pair of force and respective value of power;
 32. The method of claim 31, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a respective coefficient of determination for each of the slope values.
 33. The method of claim 32, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a best fit slope value among each of the slope values that corresponds to the highest coefficient of determination among the respective coefficients of determination.
 34. The method of claim 33, wherein determining the coefficient of friction of the tissue further comprises: determining that the highest coefficient of determination satisfies a predetermined threshold; and based on the determination that the predetermined threshold is satisfied, computing the coefficient of friction using the best fit slope value.
 35. The method of claim 30, further comprising dynamically changing the power delivery profile based on determining a change in the tissue coefficient of friction of the tissue.
 36. The method of claim 30, further comprising entering a learning mode to improve accuracy of determining the coefficient of friction.
 37. A method comprising: applying a force to tissue using an end effector of a surgical instrument; measuring, by a processor, the force applied to the tissue; comparing, by the processor, the measured force to a threshold minimum force value; measuring, by the processor, a value of power by the end effector when the end effector applies the force to the tissue; computing, by the processor, a coefficient of determination value using the value of power and the measured force; determining, by the processor, a coefficient of friction of the tissue using the coefficient of determination value; determining, by the processor, a type of tissue by comparing the determined coefficient of friction to a database relating stored coefficients of friction to predetermined types of tissue; and selecting, by the processor, a power delivery profile for delivering energy from a generator to the end effector that is suitable for performing a surgical operation on the determined type of tissue.
 38. The method of claim 37, wherein determining the coefficient of friction of the tissue comprises: applying and measuring a plurality of forces, each at different values, to the tissue using the end effector; measuring, by the processor, for each of the plurality of forces, a respective value of power; and computing, by the processor, for each pair of the plurality of forces and respective values of power, a slope value using said pair of force and respective value of power;
 39. The method of claim 38, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a respective coefficient of determination for each of the slope values.
 40. The method of claim 39, wherein determining the coefficient of friction of the tissue further comprises: determining, by the processor, a best fit slope value among each of the slope values that corresponds to the highest coefficient of determination among the respective coefficients of determination.
 41. The method of claim 40, wherein determining the coefficient of friction of the tissue further comprises: determining that the highest coefficient of determination satisfies a predetermined threshold; and based on the determination that the predetermined threshold is satisfied, computing the coefficient of friction using the best fit slope value.
 42. The method of claim 37, further comprising entering a learning mode to improve accuracy of determining the coefficient of friction. 